package quki.algorithm.dp;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.math.BigInteger;

public class BOJ1793 {

public static void main(String[] args) throws IOException{

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

while(true){

String line = br.readLine();

if(line==null) break;

int n = Integer.parseInt(line);

BigInteger d[] = new BigInteger[251];

d[0] = BigInteger.ONE;

d[1] = BigInteger.ONE;

for(int i = 2; i<= n;i++){

d[i] = d[i-1].add(d[i-2].multiply(new BigInteger("2")));

}

System.out.println(d[n]);

}

}

}