Search item into list by passing another list with where ?

public class ClassItemA
{
public string item { get; set; }
public short count { get; set; }
}
public class ClassItemB
{
public string item { get; set; }
}
class Program
{
static void Main(string[] args)
{

List b = new List();
string[] s = { "B00B0YJQPK", "B0046HF4AY" };
string[] s1 = { "B00BGL8YWS", "B0006G4MH0" };
foreach (string sb in s)
{
ClassItemA cb = new ClassItemA();
cb.item = sb.ToString();
cb.count = 10;
b.Add(cb);
}
foreach (string sb in s1)
{
ClassItemA cb = new ClassItemA();
cb.item = sb.ToString();
cb.count = 0;
b.Add(cb);
}
List c = new List();
string[] s2 = { "B00B0YJQPK", "B0046HF4AY", "B00BGL8YWS", "B0006G4MH0" };
foreach (string sb in s2)
{
ClassItemB cc = new ClassItemB();
cc.item = sb.ToString();
c.Add(cc);

}


Console.ReadLine();

}

 

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Now I have to write a linq to get the items form classItemB object where items from ClassItemA which has count > 0.

Please suggest.