infix

import re

def factor(elements):
   i = 0
   value = 1
   token = "*"
   while "/" in elements or "*" in elements:
      if elements[i+1] == "*":
         if token == "*":
            value *= int(elements[i])
         else:
            value /= int(elements[i])
         token = "*"
         elements.pop(i+1)
      elif elements[i+1] == "/":
         if token == "*":
            value *= int(elements[i])
         else:
            value /= int(elements[i])
         token = "/"
         elements.pop(i+1)
      i +=  1
   if token == "*":
      value *= int(elements[i])
   else:
      value /= int(elements[i])
   return int(value)

def expr(elements):
   i = 0
   value = 0
   token = "+"
   while  "-" in elements or "+" in elements:
      if elements[i+1] == "+":
         if token == "+":
            value += factor(elements[:i+1])
         else:
            value -= factor(elements[:i+1])
         token = "+"
         elements = elements[i+2:]
         i = 0
      elif elements[i+1] == "-":
         if token == "+":
            value += factor(elements[:i+1])
         else:
            value -= factor(elements[:i+1])
         token = "-"
         elements = elements[i+2:]
         i = 0
      i +=  1
   if token == "+":
      value += factor(elements)
   else:
      value -= factor(elements)
   return value


def infix(string1):
   tokens = re.split('(\W)',string1)
   i = 0
   while '' in tokens or ' ' in tokens[i] :
      if tokens[i] == ' ' or tokens[i] =='':
         tokens.pop(i)
      i+= 1
   i = 0
   j = 0
   while ')' in tokens:
      if tokens[i] != ")":
         i += 1
         j = i
         while tokens[j] != "(":
            j -= 1
      if tokens[i] == ")" and tokens[j] == "(":
         tokens = tokens[:j]+[str(expr(tokens[j+1:i]))]+tokens[i+1:]
         i = 0
   value = expr(tokens)
   return value
print(infix("27*((15+36)/2)-7"))