import java.io.BufferedReader;
import java.io.InputStreamReader;

public class No249 {
    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    System.in));
            int count = 0;
            for (int i = 0; i < 1000; i++) {

                long[] a = strToLongArray(br.readLine());
                long N = a[0];
                long K = a[1];
                if ((N - 1) % (K + 1) == 0) {
                    count++;
                }
            }
            System.out.println(count);
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println("Error:" + e.getMessage());
        }
    }

    static long[] strToLongArray(String S) {
        String[] strArray = S.split(" ");
        long[] longArray = new long[strArray.length];
        for (int i = 0; i < strArray.length; i++) {
            longArray[i] = Long.parseLong(strArray[i]);
        }
        return longArray;
    }
}