import java.util.*;
import java.math.*;
 
class Main
{
	public static void main (String[] args)
	{
		Scanner in = new Scanner(System.in);
		in.useDelimiter(""); //Чтение по одному символу.
		
		//String a = new String();
		int a = (int)in.next().charAt(0);  //Первый ключ
		int c1 = (int)in.next().charAt(0); //Пробел
		int b = (int)in.next().charAt(0);  //Второй ключ
		int c2 = (int)in.next().charAt(0); //Пробел
		
		while(in.hasNext()){
			c1 = (int)in.next().charAt(0);
			c2 = (int)in.next().charAt(0);
			System.out.print((char) Math.round((c1-b+256*c2)*1.0/a));
		}
	}
}