op_order = ['+', '-', '/', '*']


def evaluate(s):
    for op in op_order:
        t = s.rsplit(op, 1)
        if len(t) == 2:
            return ops[op](t[0], t[1])
    return int(s)


def divide(l, r):
    return evaluate(l) / evaluate(r)


def multiply(l, r):
    return evaluate(l) * evaluate(r)


def add(l, r):
    return evaluate(l) + evaluate(r)


def subtract(l, r):
    return evaluate(l) - evaluate(r)


ops = {
    '+': add,
    '-': subtract,
    '/': divide,
    '*': multiply,
}