#include<bits/stdc++.h>
using namespace std;
const int MAXN = 100010;
int main() {
	int n;
	cin >> n;
	vector<vector <int> > v;
	int x,l;
	for(int i = 0; i < n; i++){
		cin >> x >> l;
		v.push_back({x+l,x-l});
	}
	sort(v.begin(),v.end());
	int cnt = 1;
	int rightpos = v[0][0];
	for(int i = 1; i < v.size(); i++){
		if(v[i][1] >= rightpos){
			cnt++;
			rightpos = v[i][0];
			//cout << i << endl;
		}
	}
	cout << cnt << endl;
    return 0;
}