using System;

public class Program

{

    public static void Main()

    {

        int[] numbers = new int[]{1,2,3,5,6};

        Search search = new Search();

        Console.WriteLine(search.Position(numbers, 4));

        Console.WriteLine(search.Position(numbers, 2));

        Console.WriteLine(search.Position(numbers, 0));

        Console.WriteLine(search.Position(numbers, 7));

    }

}

​

public class Search

{

    public int Position(int[] nums, int k)

    {

        for(int i = 0; i<nums.Length; i++)

        {

            if(nums[i] >= k)

                return i;

        }

        return nums.Length;

    }

}