#include <bits/stdc++.h>
using namespace std;
int n;
const int oo = 2000000000;
vector<pair<int, int> > puntos;
int main() {
  cin >> n;
  int wi, xi;
  for (int i = 0; i < n; i++) {
    cin >> xi >> wi;
    puntos.push_back(make_pair(xi + wi, xi - wi));
  }
  sort(puntos.begin(), puntos.end());
  int ab = 0;
  int clique = 0;
  int last = -oo;
  for (int i = 0; i < n; i++) {
    if (puntos[i].second >= last) {
      last = puntos[i].first;
      clique++;
    }
  }
  cout << clique << endl;
  return 0;
}
