#include <bits/stdc++.h>
using namespace std;
int n;
long long x, w;
vector<pair<long long, long long> > ints;
void read() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x >> w;
    ints.push_back(make_pair(x + w, x - w));
  }
}
void solve() {
  sort(ints.begin(), ints.end());
  int ans = 1;
  long long lastr = ints[0].first;
  for (int i = 1; i < n; i++) {
    if (ints[i].second >= lastr) {
      ans++;
      lastr = ints[i].first;
    }
  }
  cout << ans << endl;
}
int main() {
  std::ios::sync_with_stdio(false);
  read();
  solve();
  return 0;
}
