import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long min = Long.MAX_VALUE;
        for (long i = 1; ;i++) {
            long x = (long)Math.ceil(Math.pow(a, 1.0 / i));
            min = Math.min(min, x * i);
            if (i * i > a) {
                break;
            }
        }
        System.out.println(min);
    }
}