#include <bits/stdc++.h>
using namespace std;

int main(){
    int N;
    cin >> N;
    vector<pair<int, int>> RL(N);
    for(int i=0; i<N; i++){
        int x, l;
        cin >> x >> l;
        RL[i] = {x+l, x-l};
    }
    sort(RL.begin(), RL.end());

    int ans = 0;
    int R = -2e9;
    for(auto& p : RL){
        int r = p.first, l = p.second;
        if(R <= l){
            R = r;
            ans++;
        }
    }
    cout << ans << endl;
    return 0;
}
