#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  cin >> n;
  vector<pair<int, int> > x;
  for (int i = 0; i < n; ++i) {
    int curX, curW;
    cin >> curX >> curW;
    x.push_back(pair<int, int>(curX, curW));
  }
  sort(x.begin(), x.end());
  int r = -2 * 1000 * 1000 * 1000;
  int ans = 0;
  for (int i = 0; i < x.size(); ++i) {
    int curX = x[i].first;
    int curW = x[i].second;
    if (curX - curW >= r) {
      ans++;
      r = curX + curW;
    } else if (curX + curW < r) {
      r = curX + curW;
    }
  }
  cout << ans << endl;
}
int main() {
  solve();
  return 0;
}
