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>

#define rep(i, j, k) for(int i = (int) j; i < (int) k; ++i)
#define sz(x) ((int) (x).size())
#define ll long long
#define mp make_pair
#define pii pair<int, int >
#define fi first
#define se second
#define pb push_back
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
#define zero(x) memset((x), (0), sizeof (x))
#define zerox(x, y) memset((x), (y), sizeof (x))

using namespace std;

int main()
{
#ifdef PIT
//freopen(".in", "r", stdin);
//freopen(".out", "w", stdout);
#endif //PIT

	ios_base::sync_with_stdio(false); cin.tie(0);
	int X, t;
	cin >> X >> t;
	cout << max(0, X-t) << endl;
	
#ifdef PIT
flush(cout);
cerr << endl << "Time: " << (clock() / double(CLOCKS_PER_SEC)) << endl;
#endif //PIT
	return 0;
}