#include <bits/stdc++.h>
using namespace std;
struct Node {
  int L, R;
} x[200001];
bool CMP(Node x, Node y) { return x.R < y.R; }
int main() {
  int n, i, a, b, ans, last;
  scanf("%d", &n);
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &a, &b);
    x[i].L = a - b, x[i].R = a + b;
  }
  sort(x + 1, x + 1 + n, CMP);
  ans = 1;
  last = x[1].R;
  for (i = 2; i <= n; i++) {
    if (x[i].L >= last) {
      ans++;
      last = x[i].R;
    }
  }
  printf("%d", ans);
  return 0;
}
