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;

#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define ALL(a) begin(a),end(a)
#define COUNTOF(a) (sizeof(a)/sizeof(a[0]))
#define SP << " " <<
#define FMT(a) #a<<":"<<a 
#define FMT2(a,b) #a<<":"<<a<<", "<<#b<<":"<<b 
#define FMT3(a,b,c) #a<<":"<<a<<", "<<#b<<":"<<b<<", "<<#c<<":"<<c 
#define FMT4(a,b,c,d) #a<<":"<<a<<", "<<#b<<":"<<b<<", "<<#c<<":"<<c<<", "<<#d<<":"<<d 
typedef long long ll;
template<class T> istream& operator >> (istream& s, vector<T>& v) {
  for (T& x: v) s >> x;
  return s;
}
inline void Yes(bool f=true){cout<<(f?"Yes":"No")<<endl;}
inline void YES(bool f=true){cout<<(f?"YES":"NO")<<endl;}
#define ANS(a) cout<<a<<endl

int main()
{
    cin.tie(0); ios::sync_with_stdio(false);
    //cout<<std::fixed<<std::setprecision(10);

    int X,t; cin >>X>>t;
    cout << max(0,X-t) << endl;
}