using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var ints = new List<int>{1,2,5,8};

        var otherInts = new List<int>{3,4,9};

        var intsImmediatelyLessThanOrEqualToOtherInts = from i in ints

            let firstGreaterOtherInt = otherInts.First(o => o > i)

            let intBetweenThisAndOther = from i2 in ints

                where i2 > i && i2 < firstGreaterOtherInt

                select i2

            select intBetweenThisAndOther.Count() > 0 ? null as object : i;

        intsImmediatelyLessThanOrEqualToOtherInts.Where(i => i != null).ToList().ForEach(Console.WriteLine);

    }

}