#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MOD = 1000000007;
vector<pii> ree;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = (0); i < (n); i++) {
    int x, v;
    cin >> x >> v;
    ree.push_back({x + v, x - v});
  }
  sort(ree.begin(), ree.end());
  int cl = -2e9, a = 0;
  for (int i = (0); i < (n); i++)
    if (cl <= ree[i].second) cl = ree[i].first, a++;
  cout << a << endl;
}
