#include <bits/stdc++.h>
using namespace std;
pair<int, int> a[200005];
int main() {
  int x, w, n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    scanf("%d%d", &x, &w);
    a[i] = make_pair(x + w, x - w);
  }
  sort(a, a + n);
  int r = -1e9;
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (a[i].second >= r) {
      r = a[i].first;
      ans++;
    }
  }
  cout << ans;
  return 0;
}
