two test cases pass can anyone fix this

`def longestPalindromicSubsequence(s, k):

if len(s)==1:
    return 2
if k==0:
    return 26*(len(s)+1)

def lcs(x,y,s1,s2):

    dp = [[-1] * (y + 1) for _ in range(x + 1)]

    for i in range(x+1):
        for j in range(y+1):

            if i==0 or j==0:
                dp[i][j] = 0

            elif (s1[i-1]==s2[j-1]):
                dp[i][j] = dp[i-1][j-1] + 1
            else:
                dp[i][j] = max(dp[i][j-1],dp[i-1][j] )  

    return dp[x][y]

n = len(s)
lps = lcs(n,n,s,s[::-1])

alpha = {}
for i in s:
    alpha[i] =1
count = 0
for i in alpha:
    for j in range(n):
        new_str = s[:j] + i + s[j:]
        new_len = len(new_str)
        if lcs(n+1,n+1,new_str,new_str[::-1]) >= lps+k:
            count+=1
return count`