#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
typedef pair<int, int> P;

int main() {
  int n, x, l, count = 0;
  scanf("%d", &n);
  vector<P> rs;
  rep(i, n) {
    scanf("%d %d", &x, &l);
    rs.push_back({x+l, x-l});
  }
  sort(rs.begin(), rs.end());
  int a = -100100100;
  for (auto r: rs) {
    if (a <= r.second) {
      a = r.first;
      count++;
    }
  }
  printf("%d\n", count);
  return 0;
}
