#include <bits/stdc++.h>
int main() {
  int m;
  scanf("%d", &m);
  int zhong = int(sqrt(m));
  if (zhong * zhong == m)
    printf("%d\n", 2 * zhong);
  else {
    if (m > (zhong + 1) * (zhong + 1) - zhong - 1)
      printf("%d\n", 2 * (zhong + 1));
    else
      printf("%d\n", 2 * zhong + 1);
  }
  return 0;
}
