#include <bits/stdc++.h>
using namespace std;


int main() {
  long long n;
  cin >> n;

  long long ans = 0;
  long long cur = 1;
  long long prev = n * 2;
  while (1) {
    long long d = n / cur;
    if (prev - d > 1) {
      cur++;
      ans++;
      prev = d;
    } else {
      ans += d - 1;
      break;
    }
  }
  cout << ans << '\n';
  return 0;
}