import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long max = a;
        long x = 2;
        while (true) {
            long y = 2;
            int count = 1;
            while (y < a) {
                y *= x;
                count++;
            }
            if (max > count * x) {
                max = count * x;
            } else {
                break;
            }
            x++;
       }
       System.out.println(max);
    }
}