using System;

​

public class Program

{

    public class Test

    {

        public int[] arr;

        public int target;

​

        public void Print()

        {

            int index = FindIndexOf(arr, target);

            Console.WriteLine(index);

            Console.WriteLine(arr[index] == target);

        }

    }

​

    public static void Main()

    {

        Test[] tests = new Test[]{

            new Test{

                arr = new int[]{2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1},

                target = 64

            },

            new Test{

                arr = new int[]{6, 3},

                target = 3

            },

            new Test{

                arr = new int[]{80, 40, 20, 10, 5},

                target = 20

            },

        };

​

        foreach (var test in tests)

        {

            test.Print();

        }

    }

​

    public static int FindIndexOf(int[] array, int value)

    {

        return (int)Math.Log(array[0] / value, 2);

    }

}