#include <bits/stdc++.h>
using namespace std;
const long long N = 200005;
struct ele {
  long long l, r;
} a[N];
long long n;
bool cmp(ele a, ele b) { return a.r < b.r; }
signed main() {
  long long x, l;
  cin.tie(NULL), cout.tie(NULL), ios::sync_with_stdio(false);
  cin >> n;
  if (n == 0) {
    puts("0");
    return 0;
  }
  for (long long i = 1; i <= n; ++i)
    cin >> x >> l, a[i].l = x - l + 1, a[i].r = x + l - 1;
  sort(a + 1, a + n + 1, cmp);
  long long la = a[1].r, ans = 1;
  for (long long i = 2; i <= n; ++i)
    if (a[i].l >= la) ++ans, la = a[i].r;
  cout << ans;
  return 0;
}
