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