using System;

public class Program

{

    public static void Main()

    {

                    int[] a = new int[100];

            Console.WriteLine("Number of elements in the array ?");

            string s = Console.ReadLine();

            int x = Int32.Parse(s);

            Console.WriteLine("-----------------------");

            Console.WriteLine(" Enter array elements ");

            Console.WriteLine("-----------------------");

            for (int i = 0; i < x; i++)

            {

                string s1 = Console.ReadLine();

                a[i] = Int32.Parse(s1);

            }

            Console.WriteLine("--------------------");

            Console.WriteLine("Enter Search element");

            Console.WriteLine("--------------------");

            string s3 = Console.ReadLine();

            int x2 = Int32.Parse(s3);

            int low = 0;

            int high = x - 1;

            while (low <= high)

            {

                int mid = (low + high) / 2;

                if (x2 < a[mid])

                    high = mid - 1;

                else if (x2 > a[mid])

                    low = mid + 1;

                else if (x2 == a[mid])

                {

                    Console.WriteLine("-----------------");

                    Console.WriteLine("Search successful");

                    Console.WriteLine("-----------------");

                    Console.WriteLine("Element {0} found at location {1}\n", x2, mid + 1);

                    return;

                }

            }

            Console.WriteLine("Search unsuccessful");

        }

    }

​