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