def main():
    import sys
    s = sys.stdin.readline().strip()
    n = len(s)
    if n <= 1:
        print(0)
        return
    
    # Check if the entire string is a palindrome
    is_full_palindrome = True
    for i in range(n // 2):
        if s[i] != s[n - 1 - i]:
            is_full_palindrome = False
            break
    if is_full_palindrome:
        print(n - 1)
        return
    
    max_len = 0
    
    # Check for possible max palindrome by removing one character
    for i in range(n):
        left = i - 1
        right = i + 1
        current = 0
        while left >= 0 and right < n and s[left] == s[right]:
            current += 1
            left -= 1
            right += 1
        max_len = max(max_len, 2 * current + 1)
        
        left = i
        right = i + 1
        current = 0
        while left >= 0 and right < n and s[left] == s[right]:
            current += 1
            left -= 1
            right += 1
        max_len = max(max_len, 2 * current)
    
    # Now check for removing each character and expanding around i-1 and i+1
    for i in range(1, n-1):
        if s[i-1] == s[i+1]:
            left = i - 1
            right = i + 1
            current_length = 2
            while left > 0 and right < n-1 and s[left-1] == s[right+1]:
                current_length += 2
                left -= 1
                right += 1
            max_len = max(max_len, current_length)
    
    print(max_len)

if __name__ == "__main__":
    main()