#include <bits/stdc++.h>
int main() {
  long long int b, x, y;
  scanf("%lld", &b);
  x = sqrt(b);
  y = 2 * x;
  if (x * x != b) y++;
  if (b > (x * (x + 1))) y++;
  printf("%lld\n", y);
  return 0;
}
