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.
s = input()

stack = []
validtemp = []
validseq = []

for i in range(len(s)):
    if s[i] == '(' or s[i] == '[':
        stack.append([i,-1])

    if s[i] == ')':
        if stack and s[stack[-1][0]] == '(':
            stack[-1][1] = i
            validtemp.append(stack[-1])
            stack.pop()
        else:
            for j in validtemp:
                validseq.append(j)
            stack.clear()
            validtemp.clear()

    if s[i] == ']':
        if stack and s[stack[-1][0]] == '[':
            stack[-1][1] = i
            validtemp.append(stack[-1])
            stack.pop()
        else:
            for j in validtemp:
                validseq.append(j)
            stack.clear()
            validtemp.clear()

    if i == len(s)-1:
        for j in validtemp:
            validseq.append(j)

if validseq:
    for i in range(len(validseq)-1):
        if validseq[i+1][0] - validseq[i][1] == 1:
            validseq[i+1][0] = validseq[i][0]

    brackets = []
    ans = 0
    for i in validseq:
        num = 0
        for j in range(i[0], i[1]):
            if s[j] == '[':
                num += 1
        brackets.append(num)
    for i in range(len(brackets)):
        if brackets[i] > brackets[ans]:
            ans = i
        elif brackets[i] == brackets[ans]:
            if validseq[i][1] - validseq[i][0] > validseq[ans][1] - validseq[ans][0]:
                ans = i

    print(brackets[ans])
    print(s[validseq[ans][0]:validseq[ans][1]+1])
else:
    print(0)
    print()
