#include <bits/stdc++.h>
using namespace std;
long long x, w;
vector<pair<long long, long long> > q;
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    cin >> x >> w;
    q.push_back(make_pair(x + w, x - w));
  }
  sort(q.begin(), q.end());
  long long ans = 1;
  long long f = q[0].first;
  for (int i = 1; i < n; ++i) {
    if (q[i].second >= f) {
      ans++;
      f = q[i].first;
    }
  }
  cout << ans << endl;
  return 0;
}
