#include <bits/stdc++.h>
#include <algorithm>
using namespace std;
typedef long long ll;
#define rep(n) for(ll i=0; i<n; i++)

int main()
{
  ll n;
  cin >> n;
  vector<pair<ll,ll> > v;
  rep(n)
  {
    ll x,l;
    cin >> x >> l;
    v.push_back(make_pair(x+l,x-l));
  }
  sort(v.begin(),v.end());

  ll cnt = 0;
  ll cur = LLONG_MIN;
  for (auto p:v)
  {
    if (p.second < cur) continue;
    cur = p.first;
    cnt++;
  }

  cout << cnt << endl;

  return 0;
}