#include <bits/stdc++.h>
using namespace std;
pair<int, int> p[200005];
int main() {
  int n, i, w, x, s = 0, l = -(1 << 31);
  cin >> n;
  for (i = 0; i < n; i++) cin >> x >> w, p[i] = make_pair(x + w, x - w);
  sort(p, p + n);
  for (i = 0; i < n; i++)
    if (p[i].second >= l) l = p[i].first, s++;
  cout << s;
}
