#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vii = vector<vector<int>>;
const ll LINF = 1LL << 60;
const int INF = 1 << 29;
const int MOD = 1e9 + 7;
int main() {
  int n;
  cin >> n;
  vector<pii> v(n);
  for (int i = 0; i < n; i++) {
    int x, w;
    cin >> x >> w;
    v[i] = {x + w, x - w};
  }
  sort((v).begin(), (v).end());
  int ans = 0, cur = -1e9 - 5;
  for (int i = 0; i < n; i++) {
    if (cur <= v[i].second) {
      cur = v[i].first;
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
