#include <bits/stdc++.h>
using namespace std;
pair<int, int> arr[200010];
int a, b, ans = 1;
int main() {
  pair<int, int> arr[200010];
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
    cin >> a >> b, arr[i].first = a + b, arr[i].second = a - b;
  sort(arr, arr + n);
  int tmp = arr[0].first;
  for (int i = 1; i < n; i++)
    if (arr[i].second >= tmp) ans++, tmp = arr[i].first;
  cout << ans;
}
