Problem:
Score : 100 points

Problem Statement

We have a sandglass that runs for X seconds. The sand drops from the upper bulb at a rate of 1 gram per second. That is, the upper bulb initially contains X grams of sand.

How many grams of sand will the upper bulb contains after t seconds?

Constraints

1≤X≤10^9

1≤t≤10^9

X and t are integers.

Input

The input is given from Standard Input in the following format:

X t

Output

Print the number of sand in the upper bulb after t second.

Sample Input 1

100 17

Sample Output 1

83

17 out of the initial 100 grams of sand will be consumed, resulting in 83 grams.

Sample Input 2

48 58

Sample Output 2

0

All 48 grams of sand will be gone, resulting in 0 grams.

Sample Input 3

1000000000 1000000000

Sample Output 3

0

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Specialized;
using System.Linq;
class Program
{
    static void Main(string[] args)
    {
        // 解
        int ans = 0;

        // 入力
        int[] inp = MyConsole.ReadInt(' ');

        // 処理
        ans = inp[0] - inp[1];
        if (ans < 0)
        {
            ans = 0;
        }
        
        // 出力
        MyConsole.WriteLine(ans);
    }
}

class MyConsole
{
    // 文字列または数値の入力
    public static string ReadStr() { return Console.ReadLine(); }
    public static int ReadInt() { return int.Parse(Console.ReadLine()); }
    public static long ReadLong() { return long.Parse(Console.ReadLine()); }
    public static string[] ReadStr(char sep) { return Console.ReadLine().Split(sep); }
    public static int[] ReadInt(char sep) { return Console.ReadLine().Split(sep).Select(x => int.Parse(x)).ToArray(); }
    public static long[] ReadLong(char sep) { return Console.ReadLine().Split(sep).Select(x => long.Parse(x)).ToArray(); }

    public static void WriteLine(object param) { Console.WriteLine(param); }
}