using System.CodeDom.Compiler;

using System.Collections.Generic;

using System.Collections;

using System.ComponentModel;

using System.Diagnostics.CodeAnalysis;

using System.Globalization;

using System.IO;

using System.Linq;

using System.Reflection;

using System.Runtime.Serialization;

using System.Text.RegularExpressions;

using System.Text;

using System;

​

public class Program

{   

    public static int[] OccurrencesOfElement(int[] nums, int[] queries, int x) {

        var res = new int[queries.Length];

        var indices = new List<int>();

        int index = 0;

        int prevIndex = 0;

        //Iterates through nums and determines the index of x in nums starting from indices.Count()

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

        {

            if(nums[i] == x)

            {

                indices.Add(i);

            }

        }

        //Iterates through the queries and determines the indices of the nth element of x

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

        {

            if(queries[i] - 1 < indices.Count())

            {

                res[i] = indices[queries[i] - 1];

            }

            else

            {

                res[i] = -1;

            }

        }

        return res;

    }

    public static void Main()

    {

        /*

        [1,3,1,7], queries = [1,3,2,4], x = 1

        */

        int[] nums  = {1,3,1,7};

        int[] queries = {1,3,2,4};

        int x = 1;

        var res = OccurrencesOfElement(nums, queries, x);

        Console.WriteLine("Res: ");

        foreach(var r in res)

            Console.WriteLine(r);

        //SquareNums(p, q);

        //kaprekarNumbers(p, q);

    }

}