#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > o;
int n, x, w;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x >> w;
    o.push_back(make_pair(x - w, x + w));
  }
  sort(o.begin(), o.end());
  int cnt = 1, cl = o[0].second;
  for (auto c : o) {
    if (c.first >= cl) {
      cnt++;
      cl = c.second;
    } else {
      cl = min(cl, c.second);
    }
  }
  cout << cnt;
  return 0;
}
