def longest_valid_parentheses(s):
n = len(s)
if n == 0:
return 0
dp = [0] * n
max_len = 0

for i in range(1, n):
    if s[i] == ')':
        if s[i-1] == '(':
            dp[i] = (dp[i-2] if i >= 2 else 0) + 2
        else:
            if i - dp[i-1] > 0 and s[i - dp[i-1] - 1] == '(':
                dp[i] = dp[i-1] + 2 + (dp[i - dp[i-1] - 2] if (i - dp[i-1]) >= 2 else 0)
        max_len = max(max_len, dp[i])
    elif s[i] == ']':
        if s[i-1] == '[':
            dp[i] = (dp[i-2] if i >= 2 else 0) + 2
        else:
            if i - dp[i-1] > 0 and s[i - dp[i-1] - 1] == '[':
                dp[i] = dp[i-1] + 2 + (dp[i - dp[i-1] - 2] if (i - dp[i-1]) >= 2 else 0)
        max_len = max(max_len, dp[i])
    elif s[i] == '}':
        if s[i-1] == '{':
            dp[i] = (dp[i-2] if i >= 2 else 0) + 2
        else:
            if i - dp[i-1] > 0 and s[i - dp[i-1] - 1] == '{':
                dp[i] = dp[i-1] + 2 + (dp[i - dp[i-1] - 2] if (i - dp[i-1]) >= 2 else 0)
        max_len = max(max_len, dp[i])

return max_len

s = input().strip()
print(longest_valid_parentheses(s))