#include <bits/stdc++.h>
using namespace std;
int main() {
  long N;
  cin >> N;
  if (N == 0) {
    cout << 0 << endl;
    return 0;
  }
  long l = 0;
  while (l * l < N) {
    l++;
  }
  int total = l * 2;
  if (l * (l - 1) >= N) total--;
  cout << total << endl;
}
