//package com.company;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Scanner;
import java.util.*;
import java.lang.*;

public class Main {

    public static boolean checkLetters(String s) throws IOException {
        boolean high = false, low = false;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) >= 65 && s.charAt(i) <= 92) high = true;
            if (s.charAt(i) >= 97 && s.charAt(i) <= 122) low = true;
        }
        return (high && low);
    }

    //  public static boolean isLetterOutOfRange(String )

    public static void main(String[] args) throws IOException {
        Scanner scanner = new Scanner(System.in);
        Integer a = scanner.nextInt();
        String s = scanner.next();
        Integer b = scanner.nextInt();
        if (checkLetters(s)) System.out.println("NaN");
        else {
            try {
                BigInteger dec = new BigInteger(s, a);
                System.out.println(dec.toString(b).toUpperCase());
             //   System.out.println(dec.toString());
            } catch (NumberFormatException e) {
                System.out.println("NaN");
            }
        }
    }
}