#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
const double pi = 3.14159265359;
const long long inf = 1000000000000000000LL;
inline bool cmp(const pair<int, int>& a, const pair<int, int>& b) {
  return (long long)a.first + a.second < (long long)b.first + b.second;
}
int main() {
  int n;
  cin >> n;
  vector<pair<int, int> > a(n);
  for (auto& e : a) {
    scanf("%d %d", &e.first, &e.second);
  }
  sort((a).begin(), (a).end(), &cmp);
  int ans = 0;
  int k = 0;
  for (int i = 1; i < ((int)(a).size()); i++) {
    if (a[k].first + a[k].second <= a[i].first - a[i].second) {
      ans++;
      k = i;
    }
  }
  cout << ans + 1 << endl;
  return 0;
}
