#include <bits/stdc++.h>
using namespace std;
int main(){
int N, i, ans=1, now, nowd; cin >> N; int X[N], L[N];
vector< pair<int, int> > V; 
for(i=0; i<N; i++){ cin >> X[i] >> L[i]; V.push_back(make_pair(X[i], L[i])); }
sort(V.begin(), V.end());
int len=V.size();
for(now=0, i=1; i<len; i++){
nowd=V[now].first+V[now].second;
if(nowd<=V[i].first-V[i].second){ ans++; now=i; continue; }
if(nowd<=V[i].first+V[i].second){ continue; }
now=i;
}
cout << ans << "\n";
}