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.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace NotFounds
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve();
        }

        public void Solve()
        {
            var cin = new MyInputStream();

            var X = cin.ReadInt();
            var t = cin.ReadInt();
            Console.WriteLine(Math.Max(X - t, 0));
        }
    }

    public class MyInputStream
    {
        private char separator = ' ';
        private Queue<string> inputStream;
        public MyInputStream(char separator = ' ')
        {
            this.separator = separator;
            inputStream = new Queue<string>();
        }

        public string Read()
        {
            if (inputStream.Count != 0) return inputStream.Dequeue();
            string[] tmp = Console.ReadLine().Trim().Split(separator);
            for (int i = 0; i < tmp.Length; i++)
            {
                inputStream.Enqueue(tmp[i]);
            }
            return inputStream.Dequeue();
        }
        public string ReadLine() => Console.ReadLine();
        public int ReadInt() => int.Parse(Read());
        public long ReadLong() => long.Parse(Read());
        public double ReadDouble() => double.Parse(Read());
        public string r() => Read();
        public int ri() => ReadInt();
        public long rl() => ReadLong();
        public double rd() => ReadDouble();
    }
}