a=input("문장을 입력하십시오. : ")
b=[]
b=a
t=0
u=0

while t < len(b):
    if b[t] is "[":
        u+=1
    if b[t] is "]":
        u-=1
    if u < 0:
        break
    t+=1

if u is 0:
    print("올바른 문장")
else:
    print("잘못된 입력방식")