import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class DanceLesson2
{
    public static void main(String[] args) throws IOException
    {
        BufferedReader keyboard = new BufferedReader(
                         new InputStreamReader(System.in));

        System.out.println("Enter number of male dancers:");
        String menString = keyboard.readLine( );
        int men = Integer.parseInt(menString);

        System.out.println("Enter number of female dancers:");
        String womenString = keyboard.readLine( );
        int women = Integer.parseInt(womenString);
        
        try
        {
            if (men == 0 && women == 0)
                throw new Exception("Lesson is canceled. No students.");
            else if (men == 0)
                throw new Exception("Lesson is canceled. No men.");
            else if (women == 0)
                throw new Exception("Lesson is canceled. No women.");

            // women >= 0 && men >= 0
            if (women >= men)
                System.out.println("Each man must dance with " +
                                      women/(double)men + " women.");
            else
                System.out.println("Each woman must dance with " +
                                      men/(double)women + " men.");
        }
        catch(Exception e)
        {
            String message = e.getMessage( );
            System.out.println(message);
            System.exit(0);
        }

        System.out.println("Begin the lesson.");
    }

}