题解 | #大吉大利，今晚吃鸡#

def min_steps(n):
    if n == 0:
        return 0
    else:
        # Recursive formula to calculate steps
        return 3 * min_steps(n - 1) + 2

def main():
    import sys
    input = sys.stdin.read
    data = input().strip().split()
    
    for line in data:
        if line.strip():
            n = int(line)
            print(min_steps(n))

if __name__ == "__main__":
    main()