import java.util.*;
import java.io.*;

public class travis
{
    public static void main(String[] Args)
    {
        Scanner sc = new Scanner(System.in);
        int ans = 0;
        for (int i = 0; i < 100; i++) ans = sc.nextInt();
        ans %= 10;
        if (ans == 0) ans = 10;
        System.out.println(ans);
    }
}