2. Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

def addtwonum(strings):
    list1 = []
    num = []
    flag = 0
    for i in range(len(strings)):
        if strings[i] == '+':
            lucy = strings[:i].strip().strip('(').strip(')')
            jerry  = strings[i+1:].strip().strip('(').strip(')')
    
    for i in range(len(lucy)):
        if lucy[i] == jerry[i]:
            list1.append(lucy[i])
        else:
            sum = int(lucy[i]) + int(jerry[i]) + flag
            if sum >= 10:
                flag = 1
                sum = sum-10
            else:
                flag = 0
            list1.append(str(sum))
    print(''.join(list1))
if __name__ == '__main__':
    addtwonum("(3 -> 4 -> 5) + (5 -> 6 -> 7)")