George and Accommodation

#include<iostream>
using namespace std;
int main()
{
    int room, pi, qi, cangoroom=0;
    cin >> room;
    for (int i = 0; i < room; i++)
    {
        cin >> pi >> qi;
        if (pi <= qi - 2)
        {
            cangoroom++;
        }
    }
    cout << cangoroom;
    return 0;
}