INOUTEST.cs

using System;
using System.IO;

// https://www.spoj.com/problems/INOUTEST/ #io
// Reads input and writes input quickly (and computes something simple about it).
public static class INOUTEST
{
    private static void Main()
    {
        int n = FastIO.ReadNonNegativeInt();
        for (int i = 0; i < n; ++i)
        {
            FastIO.WriteInt(FastIO.ReadInt() * FastIO.ReadInt());
            FastIO.WriteLine();
        }

        FastIO.Flush();
    }
}

// This is based in part on submissions from https://www.codechef.com/status/INTEST.
// It's assumed the input is well-formed, so if you try to read an integer when no
// integers remain in the input, there's undefined behavior (infinite loop).
public static class FastIO
{
    private const byte _null = (byte)'\0';
    private const byte _newLine = (byte)'\n';
    private const byte _minusSign = (byte)'-';
    private const byte _zero = (byte)'0';
    private const int _inputBufferLimit = 8192;
    private const int _outputBufferLimit = 8192;

    private static readonly Stream _inputStream = Console.OpenStandardInput();
    private static readonly byte[] _inputBuffer = new byte[_inputBufferLimit];
    private static int _inputBufferSize = 0;
    private static int _inputBufferIndex = 0;

    private static readonly Stream _outputStream = Console.OpenStandardOutput();
    private static readonly byte[] _outputBuffer = new byte[_outputBufferLimit];
    private static readonly byte[] _digitsBuffer = new byte[11];
    private static int _outputBufferSize = 0;

    private static byte ReadByte()
    {
        if (_inputBufferIndex == _inputBufferSize)
        {
            _inputBufferIndex = 0;
            _inputBufferSize = _inputStream.Read(_inputBuffer, 0, _inputBufferLimit);
            if (_inputBufferSize == 0)
                return _null; // All input has been read.
        }

        return _inputBuffer[_inputBufferIndex++];
    }

    public static int ReadNonNegativeInt()
    {
        byte digit;

        // Consume and discard whitespace characters (their ASCII codes are all < _minusSign).
        do
        {
            digit = ReadByte();
        }
        while (digit < _minusSign);

        // Build up the integer from its digits, until we run into whitespace or the null byte.
        int result = digit - _zero;
        while (true)
        {
            digit = ReadByte();
            if (digit < _zero) break;
            result = result * 10 + (digit - _zero);
        }

        return result;
    }

    public static int ReadInt()
    {
        // Consume and discard whitespace characters (their ASCII codes are all < _minusSign).
        byte digit;
        do
        {
            digit = ReadByte();
        }
        while (digit < _minusSign);

        bool isNegative = digit == _minusSign;
        if (isNegative)
        {
            digit = ReadByte();
        }

        // Build up the integer from its digits, until we run into whitespace or the null byte.
        int result = isNegative ? -(digit - _zero) : (digit - _zero);
        while (true)
        {
            digit = ReadByte();
            if (digit < _zero) break;
            result = result * 10 + (isNegative ? -(digit - _zero) : (digit - _zero));
        }

        return result;
    }

    public static void WriteInt(int value)
    {
        bool isNegative = value < 0;

        int digitCount = 0;
        do
        {
            int digit = isNegative ? -(value % 10) : (value % 10);
            _digitsBuffer[digitCount++] = (byte)(digit + _zero);
            value /= 10;
        } while (value != 0);

        if (isNegative)
        {
            _digitsBuffer[digitCount++] = _minusSign;
        }

        if (_outputBufferSize + digitCount > _outputBufferLimit)
        {
            _outputStream.Write(_outputBuffer, 0, _outputBufferSize);
            _outputBufferSize = 0;
        }

        while (digitCount > 0)
        {
            _outputBuffer[_outputBufferSize++] = _digitsBuffer[--digitCount];
        }
    }

    public static void WriteLine()
    {
        if (_outputBufferSize == _outputBufferLimit) // else _outputBufferSize < _outputBufferLimit.
        {
            _outputStream.Write(_outputBuffer, 0, _outputBufferSize);
            _outputBufferSize = 0;
        }

        _outputBuffer[_outputBufferSize++] = _newLine;
    }

    public static void Flush()
    {
        _outputStream.Write(_outputBuffer, 0, _outputBufferSize);
        _outputBufferSize = 0;
        _outputStream.Flush();
    }
}