def compute(number1, number2, operator):
    if operator == "+":
        return number1 + number2
    elif operator == "-":
        return number1 - number2
    elif operator == "*":
        return number1 * number2
    elif operator == "/":
        return number1 // number2
    else:
        return number1 ** number2

def evaluate_postfix(test):
    s = Stack()
    test = ' '.join(test)
    tokenList = test.split()

    for token in tokenList:
        if token not in "^*+-//":
            s.push(int(token))
        else:
            operand2 = s.pop()
            operand1 = s.pop()
            result = compute(operand1, operand2, token)
            s.push(result)
    return s.pop()