List comparison in C#

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C#

I am trying to make Boolean value as true if the main list does not contain newly added 2nd items list.

static void Main()
       {
           List<int> toUserIds = new List<int>() { 1,3,4,5};
           List<int> fromUserIds = new List<int>() { 6,1,4,3,5};
           bool isMDNUpdated = false;
           foreach (int userID in fromUserIds)
           {
               if (toUserIds.IndexOf(userID) == -1)
               {
                   isMDNUpdated = true;
                   break;
               }
           }

           Console.WriteLine(isMDNUpdated);
           Console.Read();
       }

What I have tried:

I have tried with the below code.
Could you please correct me if this code is not in proper way.

static void Main()
       {
           List<int> toUserIds = new List<int>() { 1,3,4,5};
           List<int> fromUserIds = new List<int>() { 6,1,4,3,5};
           bool isMDNUpdated = false;
           foreach (int userID in fromUserIds)
           {
               if (toUserIds.IndexOf(userID) == -1)
               {
                   isMDNUpdated = true;
                   break;
               }
           }

           Console.WriteLine(isMDNUpdated);
           Console.Read();
       }