#include <bits/stdc++.h>
using namespace std;
struct node {
  int l, r;
  friend bool operator<(node a, node b) {
    if (a.l != b.l) return a.l < b.l;
    return a.r > b.r;
  }
} a[200005];
priority_queue<node> q;
int n, m;
int ll = 0, rr = 0;
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  printf("%d\n", max(0, n - m));
}
