This Function show you how to use Intersect to create one sequence that contains the common values shared by both arrays.

public void InterSectExample()
{

int[] A = { 1,2,3,4,2,1,3,5,4,6,4,2,1,9 };

int[] B = { 1, 3, 5, 7, 8,4,10,11 };

var commonNumbers =A.Intersect(B);

Console.WriteLine("Common numbers shared by both arrays:");
foreach (var n in commonNumbers)
{
Console.WriteLine(n);
}

}