Gmail: how to find all emails sent to somebody (to:) who is not in cc or bcc?

In Gmail, I want to find all emails that I sent "to:" somebody. But I don't want to see the emails sent this person in cc: or bcc:.

When I type "to:xxx@yyy.com", Gmail returns all emails sent to this person either in "to:" or "cc:" or "bcc:". This is not what I want. I want to see only the emails sent in to:.

How can I do this ?

Thanks !