#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
    ll n;
    cin >> n;
    vector<pair<ll,ll> > v(n);
    for(ll i = 0;i < n;i++){
        ll x,l;
        cin >> x >> l;
        v[i] = (make_pair(x+l,x-l));
    }
    sort(v.begin(),v.end());
    ll ans = 1;
    ll end = v[0].first;
    for(ll i = 1;i < n;i++){
        if(v[i].second >= end){
            ans++;
            end = v[i].first;
        }
    }
    cout << ans << endl;
}