#include <bits/stdc++.h>   using namespace std;   int main() {     int n, a[100], b[100], i, c = 0;     cin >> n;     for (i = 0; i < n; i++) {       cin >> a[i] >> b[i];       if ((b[i] - a[i]) >= 2) c++;     }     cout << c;   }   