5. Balanced Brackets -> Python

Здравейте колеги,

имам затруднения с 5-та задача от допълнителните към темата Data Types and Variables. Ако може да ми дадете някоя насока в коя посока на мислене да тръгна?

Благодаря предварително, Диляна

1. Balanced Brackets

You will receive n lines. On those lines, you will receive one of the following:

Opening bracket – “(“,
Closing bracket – “)” or
Random string

Your task is to find out if the brackets are balanced. That means after every closing bracket should follow an opening one. Nested parentheses are not valid, and if two consecutive opening brackets exist, the expression should be marked as unbalanced.

Input

On the first line, you will receive n – the number of lines, which will follow
On the next n lines, you will receive “(”, “)” or another string

Output

You have to print “BALANCED”, if the parentheses are balanced and “UNBALANCED” otherwise.

Constraints

n will be in the interval [1…20]
The length of the stings will be between [1…100] characters

Examples

Input

Output

Input

Output

(

5 + 10

)

* 2 +

(

)

-12

BALANCED

12 *

)

10 + 2 -

(

5 + 10

)

UNBALANCED

number_of_lines = int(input()) opening_bracket = 0 closing_bracket = 0 is_balanced = False is_unbalanced_forever = True for i in range(number_of_lines): symbol = input() if symbol == ')' and opening_bracket == 0: is_balanced = False is_unbalanced_forever = False continue if symbol == '(': opening_bracket += 1 if opening_bracket > 1 and closing_bracket == 0: is_unbalanced_forever = False if symbol == ')': closing_bracket += 1 if opening_bracket == closing_bracket: is_balanced = True if is_balanced and is_unbalanced_forever: print('BALANCED') else: print('UNBALANCED')