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++14 (Clang 3.8.0) (judge verdict: Accepted)

#include<cstdio>
#include<map>
#include<iostream>
#include<iomanip>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<set>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)

using namespace std;

int main(){
	int x,t;cin>>x>>t;
	if(x<=t){
		cout<<"0"<<endl;
		return 0;
	}
	else cout<<x-t<<endl;
	return 0;
}