Expression Evaluator

from collections import deque


def multiply(n: list):
    result = n[0]
    for x in n[1:]:
        result *= x
    n = [int(result)]
    return n

def sums(n: list):
    result = n[0]
    for x in n[1:]:
        result += x
    n = [int(result)]
    return n


def division(n: list):
    result = n[0]
    for x in n[1:]:
        result /= x
    n = [int(result)]
    return n


def negate(n: list):
    result = n[0]
    for x in n[1:]:
        result -= x
    n = [int(result)]
    return n


OPERATORS = {
    '*': multiply,
    '+': sums,
    '/': division,
    '-': negate,
}

info = deque(input().split())
number = []

while info:
    token = info[0]
    if token not in OPERATORS.keys():
        number.append(int(info.popleft()))
    elif token in OPERATORS.keys():
        number = OPERATORS[token](number)
        info.popleft()

print(number[0])