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.Linq;
using System.Collections.Generic;

namespace program
{
    class Program
    {
        static void Main()
        {
          int[] num = Input.ScanIntArray();
          Console.WriteLine(Math.Max(0,num[0]-num[1]));
        }
    }

    static class Input
    {
        static public int ScanInt() { return int.Parse(Console.ReadLine()); }
        static public uint ScanUint() { return uint.Parse(Console.ReadLine()); }
        static public long ScanLong() { return long.Parse(Console.ReadLine()); }
        static public ulong ScanUlong() { return ulong.Parse(Console.ReadLine()); }
        static public int[] ScanIntArray() { return Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray(); }
        static public uint[] ScanUintArray() { return Console.ReadLine().Split(' ').Select(x => uint.Parse(x)).ToArray(); }
        static public long[] ScanLongArray() { return Console.ReadLine().Split(' ').Select(x => long.Parse(x)).ToArray(); }
        static public ulong[] ScanUlongArray() { return Console.ReadLine().Split(' ').Select(x => ulong.Parse(x)).ToArray(); }

        static public string ScanStr() { return Console.ReadLine(); }
        static public string[] ScanStrArray() { return ScanStr().Split(' '); }
    }

    static class MyMath
    {
        public static int GCD(int a, int b)
        {
            Func<int, int, int> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static ulong GCD(ulong a, ulong b)
        {
            Func<ulong, ulong, ulong> gcd = null;
            gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
            return a > b ? gcd(a, b) : gcd(b, a);
        }
        public static int LCM(int a, int b)
        {
            return a * b / GCD(a, b);
        }
        public static ulong LCM(ulong a, ulong b)
        {
            return a * b / GCD(a, b);
        }
    }
}