using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        string s = "abaabba";

        StringBuilder sb = new StringBuilder(s);

        bool a = true;

        for(int i = 0 , j = sb.Length -1 ; i < sb.Length/ 2; i++ , j--){

            if(sb[i] != sb[j]){

                a = false;

            }

        }

    if(a){

                Console.WriteLine("palindrom");

​

    }else{

        Console.WriteLine("not palindrom");

    }

    }

}