#include <bits/stdc++.h>
using namespace std;
const int N = 200010;
long long n, res = 1, a, b, End;
pair<long long, long long> in[N];
int main() {
  scanf("%I64d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%I64d %I64d", &a, &b);
    in[i].second = (a - b), in[i].first = a + b;
  }
  sort(in, in + n);
  End = in[0].first;
  for (int i = 1; i < n; i++) {
    if (in[i].second >= End) End = in[i].first, res++;
  }
  printf("%I64d", res);
  return 0;
}
