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 <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <unordered_set>
 
using namespace std;
 
typedef long long ll;
typedef pair<int, int> P;
static const int INF = 1000010000;
static const int NIL = -1;
static const int MOD = 1000000007;
 
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define SORT(v) sort(v.begin(), v.end());
#define pb push_back
#define mp make_pair
#define np next_permutation
#define pq priority_queue
 
int gcd(int a, int b) { int c; while (b != 0) { c = a%b; a = b; b = c; }return a; }
int lcm(int a, int b) { int c = gcd(a, b); a /= c; return a*b; }
int nCr(int a, int b) { int i, r = 1; for (i = 1; i <= b; i++) { r *= (a + 1 - i); r /= i; }return r; }
int pow(int a, int b) { int i, r = 1; for (i = 1; i <= b; i++) { r *= a; }return r; }
long long llpow(long long a, long long b) { long long i, r = 1; for (i = 1; i <= b; i++) { r *= a; }return r; }
long long llgcd(long long a, long long b) { long long c; while (b != 0) { c = a%b; a = b; b = c; }return a; }
long long lllcm(long long a, long long b) { long long c = llgcd(a, b); a /= c; return a*b; }
long long llnCr(long long a, long long b) { long long i, r = 1; for (i = 1; i <= b; i++) { r *= (a + 1 - i); r /= i; }return r; }
 
//int dx4[4] = {0,1,0,-1}, dy4[4] = {-1,0,1,0};
//int dx5[5] = {-1,0,0,0,1}, dy5[5] = {0,-1,0,1,0};
//int dx8[8] = {-1,0,1,1,1,0,-1,-1}, dy8[8] = {1,1,1,0,-1,-1,-1,0};
//int dx9[9] = {-1,0,1,1,1,0,-1,-1,0}, dy9[9] = {1,1,1,0,-1,-1,-1,0,0};

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