diff --git a/src/StatisticsWindows/gradestatistics.cpp b/src/StatisticsWindows/gradestatistics.cpp
index 6eb769d..71a564b 100644
--- a/src/StatisticsWindows/gradestatistics.cpp
+++ b/src/StatisticsWindows/gradestatistics.cpp
@@ -14,7 +14,7 @@
 
 GradeStatisticsWindow::GradeStatisticsWindow(QWidget *parent)
     : QWidget(parent)
-    , ui(new Ui::gradeStatistics)
+    , ui(new Ui::GradeStatisticsWindow)
 {
     ui->setupUi(this);
 
@@ -216,29 +216,28 @@ void GradeStatisticsWindow::on_subjectComboBox_currentIndexChanged(int index)
 
             switch (i) {
             case 2:
-                // you are stupid
-                if (virtualTable->model()->index(0, 0).data().toInt() != NULL) {
+                if (virtualTable->model()->index(0, 0).data().toInt() != 0) {
                     series->append("Незадовільно ["
                                        + virtualTable->model()->index(0, 0).data().toString() + "]",
                                    virtualTable->model()->index(0, 0).data().toInt());
                 }
                 break;
             case 3:
-                if (virtualTable->model()->index(0, 0).data().toInt() != NULL) {
+                if (virtualTable->model()->index(0, 0).data().toInt() != 0) {
                     series->append("Задовільно ["
                                        + virtualTable->model()->index(0, 0).data().toString() + "]",
                                    virtualTable->model()->index(0, 0).data().toInt());
                 }
                 break;
             case 4:
-                if (virtualTable->model()->index(0, 0).data().toInt() != NULL) {
+                if (virtualTable->model()->index(0, 0).data().toInt() != 0) {
                     series->append("Добре [" + virtualTable->model()->index(0, 0).data().toString()
                                        + "]",
                                    virtualTable->model()->index(0, 0).data().toInt());
                 }
                 break;
             case 5:
-                if (virtualTable->model()->index(0, 0).data().toInt() != NULL) {
+                if (virtualTable->model()->index(0, 0).data().toInt() != 0) {
                     series->append("Відмінно ["
                                        + virtualTable->model()->index(0, 0).data().toString() + "]",
                                    virtualTable->model()->index(0, 0).data().toInt());
diff --git a/src/StatisticsWindows/gradestatistics.h b/src/StatisticsWindows/gradestatistics.h
index a5be091..70774ec 100644
--- a/src/StatisticsWindows/gradestatistics.h
+++ b/src/StatisticsWindows/gradestatistics.h
@@ -7,7 +7,7 @@
 #include <QWidget>
 
 namespace Ui {
-class gradeStatistics;
+class GradeStatisticsWindow;
 }
 
 class GradeStatisticsWindow : public QWidget
@@ -34,7 +34,7 @@ private slots:
     void on_subjectComboBox_currentIndexChanged(int index);
 
 private:
-    Ui::gradeStatistics *ui;
+    Ui::GradeStatisticsWindow *ui;
 
     QChartView *chartView;
     QChart *chart;
diff --git a/src/StatisticsWindows/gradestatistics.ui b/src/StatisticsWindows/gradestatistics.ui
index 88a5637..f9e1e3d 100644
--- a/src/StatisticsWindows/gradestatistics.ui
+++ b/src/StatisticsWindows/gradestatistics.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>gradeStatistics</class>
- <widget class="QWidget" name="gradeStatistics">
+ <class>GradeStatisticsWindow</class>
+ <widget class="QWidget" name="GradeStatisticsWindow">
   <property name="geometry">
    <rect>
     <x>0</x>
diff --git a/src/StatisticsWindows/groupstatistics.cpp b/src/StatisticsWindows/groupstatistics.cpp
index 9e50e7f..017c02c 100644
--- a/src/StatisticsWindows/groupstatistics.cpp
+++ b/src/StatisticsWindows/groupstatistics.cpp
@@ -14,7 +14,7 @@
 
 GroupStatisticsWindow::GroupStatisticsWindow(QWidget *parent)
     : QWidget(parent)
-    , ui(new Ui::groupStatistics)
+    , ui(new Ui::GroupStatisticsWindow)
 {
     ui->setupUi(this);
 
diff --git a/src/StatisticsWindows/groupstatistics.h b/src/StatisticsWindows/groupstatistics.h
index 0214b30..20dbf72 100644
--- a/src/StatisticsWindows/groupstatistics.h
+++ b/src/StatisticsWindows/groupstatistics.h
@@ -7,7 +7,7 @@
 #include <QWidget>
 
 namespace Ui {
-class groupStatistics;
+class GroupStatisticsWindow;
 }
 
 class GroupStatisticsWindow : public QWidget
@@ -27,7 +27,7 @@ private slots:
     void clearPieChart();
 
 private:
-    Ui::groupStatistics *ui;
+    Ui::GroupStatisticsWindow *ui;
 
     QChartView *chartView;
     QChart *chart;
diff --git a/src/StatisticsWindows/groupstatistics.ui b/src/StatisticsWindows/groupstatistics.ui
index baf881f..2ebdac0 100644
--- a/src/StatisticsWindows/groupstatistics.ui
+++ b/src/StatisticsWindows/groupstatistics.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>groupStatistics</class>
- <widget class="QWidget" name="groupStatistics">
+ <class>GroupStatisticsWindow</class>
+ <widget class="QWidget" name="GroupStatisticsWindow">
   <property name="geometry">
    <rect>
     <x>0</x>
diff --git a/src/StatisticsWindows/studentstatistics.cpp b/src/StatisticsWindows/studentstatistics.cpp
index fafc7b5..d7fa581 100644
--- a/src/StatisticsWindows/studentstatistics.cpp
+++ b/src/StatisticsWindows/studentstatistics.cpp
@@ -14,7 +14,7 @@
 
 StudentStatisticsWindow::StudentStatisticsWindow(QWidget *parent)
     : QWidget(parent)
-    , ui(new Ui::studentStatistics)
+    , ui(new Ui::StudentStatisticsWindow)
 {
     ui->setupUi(this);
 
diff --git a/src/StatisticsWindows/studentstatistics.h b/src/StatisticsWindows/studentstatistics.h
index 4618178..4c3b406 100644
--- a/src/StatisticsWindows/studentstatistics.h
+++ b/src/StatisticsWindows/studentstatistics.h
@@ -8,7 +8,7 @@
 #include <QWidget>
 
 namespace Ui {
-class studentStatistics;
+class StudentStatisticsWindow;
 }
 
 class StudentStatisticsWindow : public QWidget
@@ -32,7 +32,7 @@ private slots:
     void setCurrentChart();
 
 private:
-    Ui::studentStatistics *ui;
+    Ui::StudentStatisticsWindow *ui;
 
     QChartView *chartView;
     QChart *chart;
diff --git a/src/StatisticsWindows/studentstatistics.ui b/src/StatisticsWindows/studentstatistics.ui
index 0ab6f78..7a8a268 100644
--- a/src/StatisticsWindows/studentstatistics.ui
+++ b/src/StatisticsWindows/studentstatistics.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>studentStatistics</class>
- <widget class="QWidget" name="studentStatistics">
+ <class>StudentStatisticsWindow</class>
+ <widget class="QWidget" name="StudentStatisticsWindow">
   <property name="geometry">
    <rect>
     <x>0</x>
diff --git a/src/StatisticsWindows/subjectstatistics.cpp b/src/StatisticsWindows/subjectstatistics.cpp
index e4ebd34..8309a70 100644
--- a/src/StatisticsWindows/subjectstatistics.cpp
+++ b/src/StatisticsWindows/subjectstatistics.cpp
@@ -11,7 +11,7 @@
 
 SubjectStatisticsWindow::SubjectStatisticsWindow(QWidget *parent)
     : QWidget(parent)
-    , ui(new Ui::subjectStatistics)
+    , ui(new Ui::SubjectStatisticsWindow)
 {
     ui->setupUi(this);
     setWindowTitle("Статистика предметів по типам");
diff --git a/src/StatisticsWindows/subjectstatistics.h b/src/StatisticsWindows/subjectstatistics.h
index ab886f1..0bd80d7 100644
--- a/src/StatisticsWindows/subjectstatistics.h
+++ b/src/StatisticsWindows/subjectstatistics.h
@@ -8,7 +8,7 @@
 #include <QWidget>
 
 namespace Ui {
-class subjectStatistics;
+class SubjectStatisticsWindow;
 }
 
 class SubjectStatisticsWindow : public QWidget
@@ -28,7 +28,7 @@ private slots:
     void setSystemUI();
 
 private:
-    Ui::subjectStatistics *ui;
+    Ui::SubjectStatisticsWindow *ui;
 
     QChartView *chartView;
     QChart *chart;
diff --git a/src/StatisticsWindows/subjectstatistics.ui b/src/StatisticsWindows/subjectstatistics.ui
index bd5c131..3705913 100644
--- a/src/StatisticsWindows/subjectstatistics.ui
+++ b/src/StatisticsWindows/subjectstatistics.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>subjectStatistics</class>
- <widget class="QWidget" name="subjectStatistics">
+ <class>SubjectStatisticsWindow</class>
+ <widget class="QWidget" name="SubjectStatisticsWindow">
   <property name="geometry">
    <rect>
     <x>0</x>
diff --git a/src/StatisticsWindows/teacherstatistics.cpp b/src/StatisticsWindows/teacherstatistics.cpp
index e156e42..2bdb6b3 100644
--- a/src/StatisticsWindows/teacherstatistics.cpp
+++ b/src/StatisticsWindows/teacherstatistics.cpp
@@ -11,7 +11,7 @@
 
 TeacherStatisticsWindow::TeacherStatisticsWindow(QWidget *parent)
     : QWidget(parent)
-    , ui(new Ui::teacherStatistics)
+    , ui(new Ui::TeacherStatisticsWindow)
 {
     ui->setupUi(this);
     setWindowTitle("Статистика викладачів по категоріям");
diff --git a/src/StatisticsWindows/teacherstatistics.h b/src/StatisticsWindows/teacherstatistics.h
index 9d22187..93f101e 100644
--- a/src/StatisticsWindows/teacherstatistics.h
+++ b/src/StatisticsWindows/teacherstatistics.h
@@ -8,7 +8,7 @@
 #include <QWidget>
 
 namespace Ui {
-class teacherStatistics;
+class TeacherStatisticsWindow;
 }
 
 class TeacherStatisticsWindow : public QWidget
@@ -28,7 +28,7 @@ private slots:
     void setSystemUI();
 
 private:
-    Ui::teacherStatistics *ui;
+    Ui::TeacherStatisticsWindow *ui;
 
     QChartView *chartView;
     QChart *chart;
diff --git a/src/StatisticsWindows/teacherstatistics.ui b/src/StatisticsWindows/teacherstatistics.ui
index 9b86004..8e825b7 100644
--- a/src/StatisticsWindows/teacherstatistics.ui
+++ b/src/StatisticsWindows/teacherstatistics.ui
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ui version="4.0">
- <class>teacherStatistics</class>
- <widget class="QWidget" name="teacherStatistics">
+ <class>TeacherStatisticsWindow</class>
+ <widget class="QWidget" name="TeacherStatisticsWindow">
   <property name="geometry">
    <rect>
     <x>0</x>
diff --git a/src/styles/black/StatisticsWindows/StatisticsWindows.qss b/src/styles/black/StatisticsWindows/StatisticsWindows.qss
index 696cef9..ccd6a20 100644
--- a/src/styles/black/StatisticsWindows/StatisticsWindows.qss
+++ b/src/styles/black/StatisticsWindows/StatisticsWindows.qss
@@ -1,8 +1,8 @@
-gradeStatistics,
-groupStatistics,
-studentStatistics,
-subjectStatistics,
-teacherStatistics
+GradeStatisticsWindow,
+GroupStatisticsWindow,
+StudentStatisticsWindow,
+SubjectStatisticsWindow,
+TeacherStatisticsWindow
 {
     background-color: rgb(39, 41, 42);
 }
diff --git a/src/styles/white/StatisticsWindows/StatisticsWindows.qss b/src/styles/white/StatisticsWindows/StatisticsWindows.qss
index 8364e3e..9e417ba 100644
--- a/src/styles/white/StatisticsWindows/StatisticsWindows.qss
+++ b/src/styles/white/StatisticsWindows/StatisticsWindows.qss
@@ -1,8 +1,8 @@
-gradeStatistics,
-groupStatistics,
-studentStatistics,
-subjectStatistics,
-teacherStatistics
+GradeStatisticsWindow,
+GroupStatisticsWindow,
+StudentStatisticsWindow,
+SubjectStatisticsWindow,
+TeacherStatisticsWindow
 {
     background-color: rgb(231, 224, 223);
 }