#include 
using namespace std;

int main()
{
  int n;
  cin >> n;

  pair brod[n];
  
  
    for (int i = 0; i < n; i++)
    {
        cin >> brod[i].second >> brod[i].first;
    }
  
  
    sort(brod,brod + n);
  
  
    int L = brod[0].first - brod[0].second;
    int R = brod[0].first;
  int  res = 1; 
  
  
    for(int i = 1; i < n;i++) {
  
        int l = brod[i].second;
        int p = brod[i].first;
  
        if (p >= R) {
          L = max(p - l, R);
          R = L + l;
          res++;
        } 
        else {
          int x = max(p, L + l);
          if (x < R) {
            R = x;
          }
        }
  
    }
cout << res << endl;
  return 0;
}