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

const int N = 1e5 + 3;
int n, ans;
pair<int, int> seg[N];

int main() {
	scanf("%d", &n);
	for(int i = 1; i <= n; i++) {
		int x, l; scanf("%d %d", &x, &l);
		seg[i] = make_pair(x + l, x - l);
	}
	sort(seg + 1, seg + 1 + n);
	for(int i = 1, cur = INT_MIN; i <= n; i++) 
		if(seg[i].second >= cur) ans++, cur = seg[i].first;
	printf("%d\n", ans);
	return 0;
}