Balanced Brackets

def is_balanced(expression):
    stack = []
    for char in expression:
        if char == "(":
            stack.append(char)
        elif char == ")":
            if not stack or stack[-1] != "(":
                return False
            stack.pop()

    return len(stack) == 0

n = int(input())
expression = ""

for _ in range(n):
    line = input().strip()
    expression += line

result = is_balanced(expression)
if result:
    print("BALANCED")
else:
    print("UNBALANCED")