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.Generic;
using System.Linq;
using System.Text;
class Program
{
    public static bool f = false, t = true;
    static void Main(string[] args)
    {
        int[] a = Read.ints();
        Console.WriteLine(Math.Max(0,a[0]-a[1]));
    }
    public static long gcd(long a, long b)
    {
        while (true)
        {
            if (a == 0) { return b; }
            if (b == 0) { return a; }
            if (a > b) { a -= b; }
            else { b -= a; }
        }
    }
    public static long lcm(long a, long b)
    {
        return a / gcd(a, b) * b;
    }
    public static bool IsPrime(long n)
    {
        if (n < 2) return false;
        if (n == 2) return true;

        for (long i = 2; i < n; i++)
        {
            if (n % i == 0) return false;
        }
        return true;
    }

}
public static class Read
{
    public static void outl(string n = "") { Console.WriteLine(n); return; }
    public static long Long()
    {
        return long.Parse(Console.ReadLine());
    }
    public static long[] longs()
    {
        return Console.ReadLine().Split().Select(long.Parse).ToArray();
    }
    public static int Int()
    {
        return int.Parse(Console.ReadLine());
    }
    public static int[] ints()
    {
        return Console.ReadLine().Split().Select(int.Parse).ToArray();
    }
    public static string Str() { return Console.ReadLine(); }
    public static string[] Strs() { return Console.ReadLine().Split(); }
}