#include <bits/stdc++.h>
using namespace std;
const int N = 100000 + 10;
const int M = 1000000007;
const double PI = atan(1) * 4;
const int oo = 2100000000;
int main() {
  int n;
  cin >> n;
  vector<pair<int, int> > v(n), g(n);
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &v[i].first, &v[i].second);
    int x = v[i].first;
    int w = v[i].second;
    g[i].first = x + w;
    g[i].second = x - w;
  }
  sort((g).begin(), (g).end());
  int ls = -1e9, ans = 0;
  for (int i = 0; i < n; ++i) {
    if (g[i].second >= ls) {
      ++ans;
      ls = g[i].first;
    }
  }
  cout << ans;
}
