import java.math.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();
        if(n==0) {
        	System.out.println(4);
        	return;
        }
        BigDecimal[] aa = new BigDecimal[n+1];
        aa[0]=new BigDecimal("4");
        aa[1]=new BigDecimal("3");
        for(int i=2;i<=n;i++){
        	BigDecimal a = aa[i-1].multiply(new BigDecimal("4.75"));
        	BigDecimal b = aa[i-2].multiply(new BigDecimal("3"));
        	aa[i]= a.subtract(b);
        }
        System.out.println(aa[n]);
    }
}