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