using System;

public class Program

{

    public int FindPosition(int[] nums, int n)

        {

            int count = 0;

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

            {

                if (nums[i] == n)

                {

                    count++;

                    if (count == 3)

                    {

                        return i;

                    }

                }

            }

            return -1;

        }

​

​

        public static void Main(string[] args)

        {

        int[] c = new int[] {};

​

        Console.WriteLine(new Program().FindPosition(c,4));

​

        }

}