#include <bits/stdc++.h>
const int maxBufSize = (10000000);
using namespace std;
long long int n, x, w;
vector<pair<long long int, long long int> > v;
int main() {
  long long int i, j, a, b, c, last, ans;
  cin >> n;
  for (i = 1; i <= n; ++i) {
    pair<long long int, long long int> p;
    cin >> x >> w;
    p.first = x + w;
    p.second = x - w;
    v.push_back(p);
  }
  sort(v.begin(), v.end());
  ans = 0;
  last = -1000000000000000000ll;
  for (i = 0; i <= n - 1; ++i) {
    if (v[i].second >= last) {
      ans++;
      last = v[i].first;
    }
  }
  cout << ans;
  return 0;
}
