Help me in solving PDEL problem

help
,
1

My issue

how can we not get 2 and 3 as output even though strings like “abxyzy” need 2 substrings to be removed

My code

def find_substring(s):
    n = len(s)
    longest_substring = ""
    for i in range(n):
        for j in range(i + 1, n):
            if s[i] == s[j]:
                substring = s[i:j + 1]
                if len(substring) > len(longest_substring):
                    longest_substring = substring
                    
    return longest_substring
    
t = int(input())
for _ in range(t):
    x = int(input())
    s = input()
    if(s==s[::-1]):
        print(0)
    else:
        if(len(set(s))==len(s)):
            print(-1)
        elif(s[0]==s[-1]):
            print(1)
        elif(s.count(s[0])>1 or s.count(s[-1])>1):
            g = find_substring(s)
            if(g==g[::-1]):
                print(1)
            else:
                print(2)
        else:
            g = find_substring(s)
            if(g==g[::-1]):
                print(2)
            else:
                print(3)

Problem Link: Palindrome Love Practice Coding Problem