#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, a1, p, w;
  vector<pair<long long, long long> > x;
  cin >> n;
  for (a1 = 0; a1 < n; ++a1) {
    cin >> p >> w;
    x.push_back(make_pair(p + w, p - w));
  }
  sort(x.begin(), x.end());
  long long ans = 0, fin = -1e11;
  for (a1 = 0; a1 < n; ++a1) {
    if (x[a1].second >= fin) {
      ++ans;
      fin = x[a1].first;
    }
  }
  cout << ans;
  return 0;
}
