#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int MAX = 1e5 + 5;
vector<pair<int, int> > v;
bool cmp(pair<int, int> a, pair<int, int> b) {
  return a.first + a.second < b.first + b.second;
}
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int s, w;
    cin >> s >> w;
    v.push_back(make_pair(s, w));
  }
  sort(v.begin(), v.end(), cmp);
  int last = 0, ans = 1;
  for (int i = 1; i < n; i++) {
    if (v[i].first - v[i].second >= v[last].first + v[last].second) {
      last = i;
      ans++;
    }
  }
  cout << ans;
  return 0;
}
