A bracket sequence is a string, containing only characters "(", ")", "[" and "]".

A correct bracket sequence is a bracket sequence that can be transformed into a correct arithmetic expression by inserting characters "1" and "+" between the original characters of the sequence. For example, bracket sequences "()[]", "([])" are correct (the resulting expressions are: "(1)+[1]", "([1+1]+1)"), and "](" and "[" are not. The empty string is a correct bracket sequence by definition.

A substring *s*[*l*... *r*] (1 ≤ *l* ≤ *r* ≤ |*s*|) of string *s* = *s*<sub class="lower-index">1</sub>*s*<sub class="lower-index">2</sub>... *s*<sub class="lower-index">|*s*|</sub> (where |*s*| is the length of string *s*) is the string *s*<sub class="lower-index">*l*</sub>*s*<sub class="lower-index">*l* + 1</sub>... *s*<sub class="lower-index">*r*</sub>. The empty string is a substring of any string by definition.

You are given a bracket sequence, not necessarily correct. Find its substring which is a correct bracket sequence and contains as many opening square brackets «[» as possible.
The first and the only line contains the bracket sequence as a string, consisting only of characters "(", ")", "[" and "]". It is guaranteed that the string is non-empty and its length doesn't exceed 10<sup class="upper-index">5</sup> characters.
str = input()
s = []
ans = 0
check = [0] * len(str)
pre = -1
for i in range(len(str)):
    if len(s) != 0 and ((str[i] == ']' and s[-1] == '[') or (str[i] == ')' and s[-1] == '(')):
        if pre == -1:
            pre = i-1
        else: pre-=1
        check[pre] = check[i] = 1
        s.pop()
    else:
        pre = -1
        s.append(str[i])

cnt = 0
st = 0
ss = 0
ff = 0
for i in range(len(str)):
    if check[i] == 1:
        ff = i
        if str[i] == '[':
            cnt += 1
    else:
        if cnt > ans:
            ans = cnt
            ss = st
            ff = i-1
            st = i+1
if cnt!=0:
    print(cnt)
    print(str[ss:ff+1])
else: print(0)




