#include <stdio.h>

int main(){
	
	int N, i;
	long long int a[64];
	
	a[0] = 0;
	for (i = 1; i < 36; i++){
		a[i] = 3 * a[i-1] + 2;
	}
	
	while (EOF != scanf("%d", &N)){
		
		printf("%lld\n", a[N]);
	}
	
	return 0;
}

/**************************************************************
	Problem: 2232
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1144 kb
****************************************************************/