import java.util.Scanner;
public class Main {
    public static void main(String[] args)
    {
            float s = 0f;
            double i = 0;
            double j = 0;
            double sum_d;
            double sum_u;
            Scanner in = new Scanner(System.in);
            System.out.print("Input a number your record book: \n");
            int c = in.nextInt();
            int c2 = c % 2;
            int c3 = c % 3;
            int c5 = c % 5;
            int c7 = c % 7;

            switch (c7){
                case 0:
                    i = (byte) i;
                    j = (byte) j;
                case 1:
                    i = (short) i;
                    j = (short) j;
                case 2:
                    i = (int) i;
                    j = (int) j;
                case 3:
                    i = (long) i;
                    j = (long) j;
                case 4:
                    i = (char) i;
                    j = (char) j;
                case 5:
                    i = (float) i;
                    j = (float) j;
                case 6:
                    i = i;
                    j = j;
            }

            System.out.print("Input a: ");
            int a = in.nextInt();
            System.out.print("Input b: ");
            int b = in.nextInt();
            System.out.print("Input n: ");
            int n = in.nextInt();
            System.out.print("Input m: ");
            int m = in.nextInt();

            in.close();

            for(i = a; i <= n; i++)
            {
                if(c2 == 0)
                    sum_d = i+c3;
                else
                    sum_d = i -c3;
                if(sum_d == 0)
                {
                  System.out.println("Lol");
                  break;
                }
                else {
                    for (j = b; j <= m; j++)
                    {
                        if (c5 == 0)
                            sum_u = i*j;
                         else if (c5 == 1)
                          sum_u = i/j;
                        else if (c5 == 2)
                            sum_u = i%j;
                        else if (c5 == 3)
                            sum_u = i+j;
                        else
                            sum_u = i-j;

                        s += (double) sum_u / sum_d ;
                    }
                }
            }
        System.out.println(s);
    }
}