Solution Review: An Array as a Subset of Another Array

using System;
using System.Collections.Generic;
namespace chapter_9
{
    class Program
    {
        static bool isSubset(int [] arr1, int [] arr2, int size1, int size2)
        {
            if (size2 > size1)
            {
                return false;
            }
            HashSet<int> ht = new HashSet<int>();
            // ht stores all the values of arr1
            for (int i = 0; i < size1; i++)
            { 
                // following the last element of the container
                // If key is not present in the unordered_set then insert it
                if (!ht.Contains(arr1[i]))
                    ht.Add(arr1[i]);
            }
            // loop to check if all elements of arr2 are also in arr1
            for (int i = 0; i < size2; i++)
            {
                // If key is not found condition will return false
                // If found it will return iterator to that key
                if (!ht.Contains(arr2[i]))
                    return false;
            }
            return true;
        }
        static void Main(string[] args)
        {
            int []arr1 = { 9, 4, 7, 1, -2, 6, 5 };
            int []arr2 = { 7, 1, -2 };
            Console.WriteLine(isSubset(arr1, arr2, 7, 3));
            return;
        }
    }
}