def solve():
    s = input().strip()
    n = len(s)
    
    if s == s[::-1]:
        print(n-1)
        return
    
    max_len = 1
    # Check for odd length palindromes
    for i in range(n):
        l, r = i-1, i+1
        current = 1
        while l >= 0 and r < n and s[l] == s[r]:
            current += 2
            l -= 1
            r += 1
        max_len = max(max_len, current)
    
    # Check for even length palindromes
    for i in range(n-1):
        if s[i] == s[i+1]:
            l, r = i-1, i+2
            current = 2
            while l >= 0 and r < n and s[l] == s[r]:
                current += 2
                l -= 1
                r += 1
            max_len = max(max_len, current)
    
    candidate = 0
    # Check around each possible i for deletion creating a new palindrome
    for i in range(1, n-1):
        if s[i-1] == s[i+1]:
            l, r = i-2, i+2
            current = 2
            while l >= 0 and r < n and s[l] == s[r]:
                current += 2
                l -= 1
                r += 1
            candidate = max(candidate, current)
    
    # Check even case deletions
    for i in range(n-1):
        if s[i] == s[i+1]:
            l, r = i-1, i+2
            current = 2
            while l >= 0 and r < n and s[l] == s[r]:
                current += 2
                l -= 1
                r += 1
            candidate = max(candidate, current)
    
    print(max(max_len, candidate))

solve()