using System;

public class Program

{

    public static void Main()

    {

        double sum =0;

        for(int i=1;i<=12;i++)

        {

            Console.WriteLine("enter a");

            int a=int.Parse(Console.ReadLine());

            Console.WriteLine("enter b");

            int b=int.Parse(Console.ReadLine());

            sum=sum+(double)a/b;    

        }

        Console.WriteLine(sum);

    }

}