UVa 1647

import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        BigInteger[] arr = new BigInteger[1001];
        arr[1] = BigInteger.valueOf(0);
        arr[2] = BigInteger.valueOf(1);
        for(int i=3; i < 1001; i++){
            arr[i] = arr[i-1].multiply(BigInteger.valueOf(2));
            if(i % 2 == 0){
                arr[i] = arr[i].add(BigInteger.valueOf(1));
            }
            else{
                arr[i] = arr[i].subtract(BigInteger.valueOf(1));
            }
        }

        Scanner in = new Scanner(System.in);

        while(in.hasNext()){
            int b;
            b = in.nextInt();
            System.out.println(arr[b]);
        }
    }
}