04. Balanced Brackets

n = int(input())
open_brackets = 0

for i in range(n):
    bracket = input()
    if bracket == ")":
        open_brackets -= 1
        if open_brackets < 0:
            break
    elif bracket == "(":
        open_brackets += 1
        if open_brackets > 1:
            break

if open_brackets == 0:
    print("BALANCED")
else:
    print("UNBALANCED")