#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	int n, k;
	int win = 0;

	for (int i = 0; i < 1000; i++) {
		cin >> n >> k;
		int tmp = n % (k + 1);
		if ((i % 2 == 0 && tmp != 1) ||
		    (i % 2 == 1 && tmp == 1)){
			win++;
		}
	}
	cout << win << endl;
	return 0;
}