#include <bits/stdc++.h>
using namespace std;
bool comp(pair<int, int> a, pair<int, int> b) { return a.second < b.second; }
int main() {
  int n, w, x;
  cin >> n;
  vector<pair<int, int> > a(n);
  for (int i = (0); i < (n); i++) {
    cin >> x >> w;
    a[i].first = x - w;
    a[i].second = x + w;
  }
  sort(a.begin(), a.end(), comp);
  int res = 0, p1 = 0, p2;
  while (p1 < a.size()) {
    res++;
    p2 = p1;
    while (p2 < n && a[p2].first < a[p1].second) p2++;
    p1 = p2;
  }
  cout << res << endl;
  return 0;
}
