#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r, s1, s2, d;
  cin >> n;
  r = ceil(double(sqrt(n)));
  s1 = r * r;
  s2 = (r - 1) * (r - 1);
  d = s1 - s2;
  d = d / 2;
  d = s1 - d;
  if (n < d) {
    cout << (r * 2) - 1;
  } else {
    cout << r * 2;
  }
}
