467A - George and Accommodation

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;

int main() {

    int n, p, q;
    int ans = 0;
    cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> p >> q;
        if(q - p >= 2) ans++;
    }
    cout << ans << endl;
    return 0;
}