分析一波

import java.util.Scanner;

public class T_test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int sum = 1;
        // 多分解几个数就会发现，全分解为2或者3时，乘积最大
        if (n <= 0) {
            System.out.print(0);
        } else if (n > 0 && n <= 2) {
            System.out.print(1);
        } else if (n == 3) {
            System.out.print(3);
        } else if (n == 4) {
            System.out.print(4);
        } else {
            while (n > 4) {
                sum *= 3;
                n = n - 3;
            }
            // 这时n的值可能为2，3，4
            if (n >= 2) 
                sum *= n;
            System.out.print(sum);
        }
    }
}