#include <bits/stdc++.h>
using namespace std;
struct node {
  int l, r;
} e[200010];
bool operator<(node t1, node t2) { return t1.r < t2.r; }
int n, ans;
int main() {
  scanf("%d", &n);
  int w, x;
  for (int i = 1; i <= n; i++) {
    scanf("%d%d", &x, &w);
    e[i].l = x - w;
    e[i].r = x + w;
  }
  sort(e + 1, e + n + 1);
  int L = -0x7fffffff;
  for (int i = 1; i <= n; i++) {
    if (e[i].l >= L) {
      ans++;
      L = e[i].r;
    }
  }
  printf("%d\n", ans);
  return 0;
}
