#include <bits/stdc++.h>
using namespace std;
 
int main() {
  int N;
  cin >>N;
  int X,L;
  vector<pair<int,int>> Robot(N); 
  for (int i=0;i<N;i++){
    cin>>X>>L;
    Robot[i].first=X+L;
    Robot[i].second=X-L;
  }
  sort(Robot.begin(),Robot.end());
  int ans=1;
  int nagasa=Robot[0].first;
  for (int i=0;i<N;i++){  
    if (nagasa<=Robot[i].second){
      ans++;
      nagasa=Robot[i].first;
    }
  }
  cout<<ans<<endl;
}