def main():

def get_list():
    list = []
    user_input = ""

    while len(user_input) >= 20 or len(user_input) <= 0:
        user_input = input("Enter: ")

    user_input = user_input.split(" ")
    for i in range(0, len(user_input)):
        if not len(user_input[i]) == 0:
            try:
                user_input[i] = int(user_input[i])
                list.append(user_input[i])

            except ValueError:
                print("Must be an integer...")

    return list

def get_result(list):
    result = 0
    list = list[0 : len(list): 2]

    for i in range(0, len(list)):
        if i == len(list) - 1:
            continue
        result += list[i]

    if len(list) > 1:
        for y in range(0, len(list)):
            if y + 1 == len(list):
                result = result * list[y]

    elif len(list) == 1:
        result = result ^ 2

    return result


def start():
    a = get_list()
    print (get_result(a))

start()

while True: main()