diff --git a/atcoder/joi2025yo1a/a.rs b/atcoder/joi2025yo1a/a.rs
new file mode 100644
index 00000000..76c0c5af
--- /dev/null
+++ b/atcoder/joi2025yo1a/a.rs
@@ -0,0 +1,10 @@
+fn getline() -> String {
+    let mut ret = String::new();
+    std::io::stdin().read_line(&mut ret).ok().unwrap();
+    ret
+}
+
+fn main() {
+    let a: i32 = getline().trim().parse().unwrap();
+    println!("{}", a / 5);
+}
diff --git a/atcoder/joi2025yo1a/b.rs b/atcoder/joi2025yo1a/b.rs
new file mode 100644
index 00000000..5f053a73
--- /dev/null
+++ b/atcoder/joi2025yo1a/b.rs
@@ -0,0 +1,14 @@
+fn getline() -> String {
+    let mut ret = String::new();
+    std::io::stdin().read_line(&mut ret).ok().unwrap();
+    ret
+}
+
+fn main() {
+    let x: i32 = getline().trim().parse().unwrap();
+    let mut s = x / 2;
+    if x % 2 == 1 {
+        s += 3;
+    }
+    println!("{s}");
+}
diff --git a/atcoder/joi2025yo1a/c.rs b/atcoder/joi2025yo1a/c.rs
new file mode 100644
index 00000000..5a610897
--- /dev/null
+++ b/atcoder/joi2025yo1a/c.rs
@@ -0,0 +1,19 @@
+fn getline() -> String {
+    let mut ret = String::new();
+    std::io::stdin().read_line(&mut ret).ok().unwrap();
+    ret
+}
+
+fn main() {
+    getline();
+    let mut s = String::new();
+    for c in getline().trim().chars() {
+        s.push(match c {
+            'J' => 'O',
+            'O' => 'I',
+            'I' => 'J',
+            _ => panic!(),
+        });
+    }
+    println!("{s}");
+}
diff --git a/atcoder/joi2025yo1a/d.rs b/atcoder/joi2025yo1a/d.rs
new file mode 100644
index 00000000..9bd1ef6f
--- /dev/null
+++ b/atcoder/joi2025yo1a/d.rs
@@ -0,0 +1,45 @@
+// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
+macro_rules! input {
+    ($($r:tt)*) => {
+        let stdin = std::io::stdin();
+        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
+        let mut next = move || -> String{
+            bytes.by_ref().map(|r|r.unwrap() as char)
+                .skip_while(|c|c.is_whitespace())
+                .take_while(|c|!c.is_whitespace())
+                .collect()
+        };
+        input_inner!{next, $($r)*}
+    };
+}
+
+macro_rules! input_inner {
+    ($next:expr) => {};
+    ($next:expr,) => {};
+    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
+        let $var = read_value!($next, $t);
+        input_inner!{$next $($r)*}
+    };
+}
+
+macro_rules! read_value {
+    ($next:expr, [ $t:tt ; $len:expr ]) => {
+        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
+    };
+    ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error"));
+}
+
+fn main() {
+    input! {
+        n: usize, m: usize,
+        a: [i32; n],
+        b: [i32; m],
+    }
+    let mut s = 0;
+    for i in 0..n {
+        for j in 0..m {
+            s += (a[i] + b[j]) * a[i].max(b[j]);
+        }
+    }
+    println!("{s}");
+}