题解 | #跳台阶扩展问题#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {

    public static int jump(int n){
        if(n<=2){
            return n; 
        }
        return jump(n-1)*2;
    }

    public static int jump1(int n){
        if(n<=2){
            return n;
        }
        int []dp = new int[n+1];
        dp[1] = 1;
        dp[2] = 2;
        for(int i=3;i<=n;i++){
            dp[i] = 2*dp[i-1];
        }
        return dp[n];
    }

    public static int get(int i){
        if(i==1)return 1;
        int result=0;
        for(--i;i>0;i--){
            result+=get(i);
        }
        return result+1;
    }


    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        int sum = sc.nextInt();
        int c = get(sum);
        
        System.out.println(c);
    }

}