class Solution {
public:

    bool checkPalandrome(string s , int st , int e){
        if (st >= e)
    {
        return true;
    }
    else if (!isalnum(s[st]))
    {
        return checkPalandrome(s, st + 1, e);
    }
    else if (!isalnum(s[e]))
    {
        return checkPalandrome(s, st, e - 1);
    }
    else if (tolower(s[st]) != tolower(s[e]))
    {
        return false;
    }
    return checkPalandrome(s, st + 1, e - 1);
    }

    bool isPalindrome(string s) {
        return  checkPalandrome(s,0,s.size()-1);
    }
};