#include<bits/stdc++.h>
 
using namespace std;
 
int main() {
 	int n;
  	cin >> n;
  	pair<int, int> a[n];
  	for (int i = 0; i < n; i++) {
    	int x, l;
      	cin >> x >> l;
      	a[i] = {x + l, x - l};
    }
  	sort(a, a + n);
  	int end = -(1e9 + 2);
  	int ans = 0;
  	for (auto x : a) {
    	if (x.second >= end) {
        	ans++;
          	end = x.first;
        }
    }
  	cout << ans;
}