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 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define VSORT(v) sort(v.begin(), v.end())
#define DVSORT(v) sort(v.begin(), v.end(),greater<int>())
#define SORT(v, n) sort(v, v+n)
#define DSORT(v,n) sort(v, v+n,greater<int>())
#define vi vector<int>
#define pb push_back
#define P pair<int,int>


template <class T> void chmin(T&a, const T&b) { a = min(a,b); }
template <class T> void chmax(T&a, const T&b) { a = max(a,b); }

const double EPS =1e-9;
const long INF =999999999;
const long MOD =1000000007; //10^9+7
#define PI 3.14159265258979

int dy[]={0, 0, 1, -1, 1, 1, -1, -1};
int dx[]={1, -1, 0, 0, 1, -1, -1, 1};

int main(){
	int X,t;
	cin>>X>>t;

	printf("%d\n",max(0,X-t));

	return 0;
}