a = list(input().split())

number = []

while (a != []):

    op_or_int = a.pop(0)

    try:  # int

        eval(op_or_int)

        number.append(op_or_int)

    except:  # op

        count = number.pop()

        count1 = number.pop()

        number.append(str(eval(count1+op_or_int+count)))

print(format(float(number[0]),".0f"))