#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, ans = 0;
  vector<pair<long long, long long> > v;
  cin >> n;
  for (int i = 0; i < n; i++) {
    long long a, b;
    cin >> a >> b;
    v.push_back(make_pair(a + b, a - b));
  }
  sort(v.begin(), v.end());
  long long last = -1e10;
  for (int i = 0; i < n; i++)
    if (v[i].second >= last) {
      ans++;
      last = v[i].first;
    }
  cout << ans << endl;
  return 0;
}
