George and Accommodation.cpp

#include<iostream>
using namespace std;
int main(){
	int n;
	cin>>n;
	int p, q;
	int count=0;
	for (int i=0; i<n; i++){
		cin>>p>>q;
		if ((q-p)>=2)
			count++;
	}
	cout<<count;
	return 0;
}