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());
		int n = s.size();
		boolean F = false;
		
		for (int i=0; i<=n; i++) {
			if (i<=n/2) {s.add(i,s.get(n-i-1));}
			else {s.add(i,s.get(n-i));}
			
			boolean b = true;
			for (int j=0; j<(n+1)/2; j++) {
				if (s.get(j)!=s.get(n-j-1)) {b=false;}
			}
			if (b==true) {F=true; break;}
			s.remove(i);
		}
		
		if (F==false) {System.out.println("NA");}
		else {
			StringBuilder ans = new StringBuilder();
			for (char c : s) {ans.append(c);}
			System.out.println(ans.toString());
		}
	}
	
	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;
	}
}