#include <iostream>

using namespace std;

int main(){

	int N,K;
	int wincounter = 0;
	int myTurn = 1;

	for(int i = 0;i < 1000; i++){
		cin >> N >> K;
		if(!(N-1)%(K+1) == 0 && myTurn)wincounter++;
		myTurn = !myTurn;
	}

	cout << wincounter;

	return 0;
}