#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
#define SQR(X) ((X)*(X))

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;
/* ここからが本編 */

int main(void)
{
  int i,j;
  int n,k;
  int cnt = 0;
  rep(i,1000) {
    cin >> n >> k;
    cnt += ( n%(k+1) ) != 1;
  }
  cout << cnt << endl;
  return 0;
}