#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, m;
  cin >> n;
  m = sqrt(n);
  if (n == 2) {
    cout << 3;
    return 0;
  }
  if (n == 3) {
    cout << 4;
    return 0;
  }
  if (m * m == n)
    cout << 2 * m;
  else if ((m * m + m) >= n)
    cout << 2 * m + 1;
  else
    cout << 2 * (m + 1);
  return 0;
}
