#include <bits/stdc++.h>
using namespace std;
long long n, x, w;
pair<long long, long long> p[200005];
int main() {
  ios::sync_with_stdio(0);
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x >> w;
    p[i] = {x + w, x - w};
  }
  sort(p, p + n);
  int ans = 0;
  long long cur = -(1ll << 55);
  for (int i = 0; i < n; i++)
    if (p[i].second >= cur) {
      cur = p[i].first;
      ans++;
    }
  cout << ans;
}
