class Solution {
public:
    bool isPalindrome(string s) {
        transform(s.begin(), s.end(), s.begin(), ::tolower);

        string ans;

        for(int i=0;i<s.size();i++){
            if((s[i]>='a'&&s[i]<='z')||(s[i]>='0'&&s[i]<='9')){
                ans=ans+s[i];
            }
        }

        string rev=ans;
        reverse(rev.begin(),rev.end());

        return rev==ans;
    }
};