#include <bits/stdc++.h>
using namespace std;
int n, dl, ld, ml, ans = 1;
struct A {
  int l, r;
} a[200006];
bool cmp(A x, A y) { return x.r < y.r; }
int main() {
  scanf("%d", &n);
  register int i;
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &dl, &ld);
    a[i].l = dl - ld;
    a[i].r = dl + ld;
  }
  sort(a + 1, a + n + 1, cmp);
  ml = a[1].r;
  for (i = 2; i <= n; i++)
    if (a[i].l >= ml) {
      ans++;
      ml = a[i].r;
    }
  printf("%d\n", ans);
  return 0;
}
