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;
using System.Threading.Tasks;

namespace A
{
    class Program
    {
        public static void Main(string[] args)
        {
            var c = ReadLineIntSpilit();
            var result = 0;

            if(c[0]-c[1] > 0) {
                result = c[0]-c[1];
            }

            Console.WriteLine(result);
            ReadLine();
        }

        /// <summary>
        /// stringを一文字ずつintにキャストして配列に変換します。
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public static int[] StringCharArrayIntArray(string str)
        {
            List<int> b = new List<int>();
            for (int i = 0; i < str.Length; i++) {
                b.Add( int.Parse(str[i].ToString()));
            }
            return b.ToArray();
        }

        public static string ReadLine()
        {
            return Console.ReadLine();
        }

        public static int ReadLineInt()
        {
            return int.Parse(Console.ReadLine());
        }

        public static string[] ReadLineStringSplit(char a = ' ')
        {
            return ReadLine().Split(a).ToArray();
        }

        public static int[] ReadLineIntSpilit(char a = ' ')
        {
            return ReadLine().Split(a).Select(x => int.Parse(x)).ToArray();
        }
    }
}