#include <bits/stdc++.h>
const int MAXX = 1000005;
const int maxInt = 2147483647;
using namespace std;
int main() {
  int n;
  cin >> n;
  int x = sqrt(n);
  if (x * x == n) {
    cout << 2 * x << '\n';
    return 0;
  } else if (x * x + x + 1 > n) {
    cout << 2 * x + 1 << '\n';
    return 0;
  } else
    cout << 2 * x + 2 << '\n';
  return 0;
}
