#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int n;
  int root;
  int res;
  cin >> n;
  root = sqrt(n);
  if (sqrt(n) == root)
    res = 2 * root;
  else {
    if ((n > root * root) && n <= root * (root + 1))
      res = 2 * root + 1;
    else {
      res = 2 * (root + 1);
    }
  }
  cout << res << '\n';
}
