import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		List<Character> s = split(sc.next());
		
		List<Character> key = new ArrayList<>();
		for (int i=0; i<s.size(); i++) {
			key.add(s.get(s.size()-i-1));
		}
		key.add(key.size()/2,key.get(key.size()/2));
		
		boolean F = false;
		for (int i=0; i<key.size(); i++) {
			s.add(i,key.get(i));
			if (IsPalindrome(s)==true) {F=true; break;}
			s.remove(i);
		}
		
		if (F==false) {System.out.println("NA");}
		else {s.forEach(x->System.out.print(x));}
	}
	
	static List<Character> split (String s){
		List<Character> list = new ArrayList<>();
		for (int i=0; i<s.length(); i++) {
			list.add(s.charAt(i));
		}
		return list;
	}
	
	static boolean IsPalindrome (List<Character> list) {
		int count = 0;
		for (int i=0; i<list.size()/2; i++) {
			if (list.get(i)==list.get(list.size()-i-1)) {count++;}
		}
		if (count==list.size()/2) {return true;}
		else {return false;}
	}
}