#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
typedef pair<int,int> P;
const int INF=1e9+7;

int main() {
	int N,X,L,p=-INF,a=0;
	cin >> N;
	vector<P> r(N);

	rep(i,N) {
		cin >> X >> L;
		r.at(i) = P(X+L, X-L);
	}
	sort(r.begin(), r.end());

	rep(i,N)
		if(p <= r.at(i).second) {
			++a;
			p = r.at(i).first;
		}

	cout << a << endl;
}