A. George and Accommodation Solution

#include<bits/stdc++.h>

using namespace std;

int main(){

    int n;

    int count=0;

    int a,b;

    cin>>n;

    while(n--){

        cin>>a>>b;

        if (b-a>=2)

            count++;

    }

    cout<<count<<endl;

    return 0;

}