import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int a = 1000;
		int[] n = new int[a];
		int[] k = new int[a];
		int counter = 0;

		for(int i = 0; i < a; i++){
			n[i] = sc.nextInt();
			k[i] = sc.nextInt();

			if((n[i] - 1) % (k[i] + 1) != 0){
				counter++;
			}
		}
		System.out.println(counter);
	}
}