#include<cstdio>
#include<vector>
#include<algorithm>

#define p1 first
#define p2 second

using namespace std;


int main()
{
  vector< pair<int,int> > l,r;

  int n;
  scanf("%d",&n);
  l.clear(); r.clear();    
  for(int i=0;i<n;i++)
  {
    int tr,tl;
    scanf("%d %d",&tl, &tr);
    l.push_back( make_pair(tl,i) );
    r.push_back( make_pair(tr+tl-1,i) );
  }
  
  sort(l.begin(),l.end());
  sort(r.begin(),r.end());
  
  vector<int> otvoren;
  int bio[50000]={0};
  int rez=0;
  for(int i1=0,i2=0;i2<n;)
  {
    if(i1<n && l[i1].p1<=r[i2].p1) otvoren.push_back(l[i1++].p2);
    else 
    {
      if(bio[ r[i2].p2 ] == 0)
      {
        rez++;
        for(int j=0;j<otvoren.size();j++) bio[otvoren[j]]=1;
        otvoren.clear();
      }
      i2++;
    }      
  }
  printf("%d\n",rez);
  return 0;
}