List manipulations

Hi,

I am trying to check whether an item from one list exists in another list.

Example:

LIST1={"John", "Alex" , "Paul"} ;
LIST2={"John", "Alex"} ;

for each ITEM in LIST2
{
     if(ITEM not in LIST1)
     {

     }
}

When I try to save this script I get an error message on the If-statement:

"Left expression should be a field name for 'not in' operator"

What am I doing wrong?

Best regards,

Ivan