Simple expression

Description.txt

Write a simple parser to parse a formula and calculate the result. Given a string containing only integer numbers, brackets, plus and minus signs, calculate and print the numeric answer. Assume that the formula will always follow correct syntax

Example input:
(2+2)-(3-(6-5))-4

Example output:
-2

FinalAnswer.py

def compute_expression(expr):
    # Write your code here
    # To print results to the standard output you can use print
    # Example: print "Hello world!"
    offset = 0
    while ')' in expr:
        close_bracket = expr.find(')')
        open_bracket = expr.rfind('(', 0, close_bracket-1)
        expr = expr[:open_bracket].strip('(') + do_math(expr[open_bracket:close_bracket]) + expr[close_bracket+1:]
    print do_math(expr)


def do_math(expr):
    return str(eval(expr))