def highestValuePalindrome(s, n, k):
    # Convert the string to a mutable list
    s = list(s)
    # Step 1: Identify mismatched mirrored pairs
    mismatches = []
    for i in range(n // 2):
        if s[i] != s[n - i - 1]:
            mismatches.append((i, n - i - 1))

    # Step 2: Check if we have enough changes to fix all mismatches
    if len(mismatches) > k:
        return "-1"  # Not enough changes to make it a palindrome

    # Step 3: Fix mismatched mirrored pairs
    for i, j in mismatches:
        # Use the larger of the two digits to fix the mismatch
        s[i] = s[j] = max(s[i], s[j])
        k -= 1  # Count this as one change

    # Step 4: Maximize the palindrome using remaining changes
    for i in range(n // 2):
        if k <= 0:
            break

        # If the current pair is not already '9', we can try to maximize it
        if s[i] != '9':
            # If this pair was previously fixed, it costs 1 change
            if (i, n - i - 1) in mismatches:
                s[i] = s[n - i - 1] = '9'
                k -= 1
            # If this pair was already a match, it costs 2 changes
            elif k >= 2:
                s[i] = s[n - i - 1] = '9'
                k -= 2

    # If the string has an odd length, we can change the middle character
    if n % 2 == 1 and k > 0:
        s[n // 2] = '9'

    # Return the resulting palindrome
    return ''.join(s)