#include<iostream>
#include<cstdio>
using namespace std;
int n;
int a[100],l;
void add(){
	int in = 0;
	for(int i = 0; i < l; i++){
		a[i] = a[i]*2+in;
		if(i==0) a[i]+=2;
		in = a[i]/10;
		a[i] = a[i]%10;
	}
	if(in){
		a[l] = in;
		l++;
	}
}
int main(){
	a[0] = 2;
	l = 1;
	cin >> n;
	for(int i = 2; i <= n; i++){
		add();
	}
	for(int i = l-1; i >= 0; i++){
		cout << a[i];
	}
	return 0;
}

输出: