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, st, se, q = input(), [], [], []

for i in range(len(s)):
    t = s[i]
    if not st and (t ==')' or t == ']'):
        continue
    if t == '(' or t == '[':
        st.append(t)
        se.append(t)
    elif t == ')' or t == ']':
        p = st.pop()
        if p == '(' and t == ')':
            se.append(t)
            if i == len(s)-1:
                lo = "".join(se)
                q.append(lo)
        elif p == '[' and t == ']':
            se.append(t)
            if i == len(s)-1:
                lo = "".join(se)
                q.append(lo)
        elif p == '(' and t == ']' or p == '[' and t == ']':
            se.pop(0)
            st = []
            lo = "".join(se)
            q.append(lo)
            q = []
if q:
    length =[]
    for i in q:
        length.append(i.count('['))
    print(max(length))
    print(q[length.index(max(length))])
else:
    print(0)