#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Field = vector<vector<int>>;
using Graph = vector<vector<int>>;
using VI = vector<int>;
using VC = vector<char>;
using PI = pair<int, int>;
const int mod = 1000000007;
struct Point {
  int x, w;
};
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<Point> p(n);
  for (int i = 0; i < (n); i++) cin >> p.at(i).x >> p.at(i).w;
  sort(p.begin(), p.end(), [](const Point lp, const Point rp) {
    return lp.x + lp.w < rp.x + rp.w;
  });
  int pt = p.at(0).x + p.at(0).w;
  int ans = 1;
  for (int i = 1; i < n; i++) {
    if (pt <= p.at(i).x - p.at(i).w) {
      ans++;
      pt = p.at(i).x + p.at(i).w;
    }
  }
  cout << ans << endl;
  return 0;
}
