__author__ = 'pranav.ambhore'

expr = raw_input("Enter a valid expression")

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

expr_list = ['']
operator_list = []

expr = expr.replace(' ', '')

i = 0
for ch in expr:
    if ch in operators:
        expr_list.append(ch)
        i += 1
        expr_list.append('')
        i += 1
    else:
        expr_list[i] += ch

print expr_list

post_expr_list = []

i = 0
for item in expr_list:
    if item not in operators:
        post_expr_list.append(item)
        i += 1
    elif item in ['+', '-']:
        operator_list.append(item)
        i += 1
    else:
        i += 1
        post_expr_list.append(expr_list[i])
        del expr_list[i]
        post_expr_list.append(item)

post_expr_list.extend(list(reversed(operator_list)))

print post_expr_list
operand_list = []
operator_list = []

for item in post_expr_list:
    if item not in operators:
        operand_list.append(item)
    else:
        opr1 = int(operand_list.pop())
        opr2 = int(operand_list.pop())
        if item == '+':
            operand_list.append(opr1 + opr2)
        if item == '-':
            operand_list.append(opr2 - opr1)
        if item == '*':
            operand_list.append(opr1 * opr2)
        if item == '/':
            operand_list.append(opr2 / opr1)

print(operand_list)