import sys

def solve():
    """
    Standard CP format for Longest Palindromic Subsequence.
    Input: A single string on one line.
    Example: BBABCBCAB
    """
    s = sys.stdin.readline().strip()
    if not s:
        return

    n = len(s)
    # Initialize DP table (n x n) with zeros
    dp = [[0 for _ in range(n)] for _ in range(n)]
    
    # Base case: every single character is a palindrome of length 1
    for i in range(n):
        dp[i][i] = 1
        
    # Build the table for substring lengths from 2 up to n
    for length in range(2, n + 1):
        for i in range(n - length + 1):
            j = i + length - 1
            if s[i] == s[j] and length == 2:
                dp[i][j] = 2
            elif s[i] == s[j]:
                dp[i][j] = dp[i+1][j-1] + 2
            else:
                dp[i][j] = max(dp[i+1][j], dp[i][j-1])
                
    print(f"Length of LPS = {dp[0][n-1]}")

if __name__ == '__main__':
    solve()