Need to get list of Mailboxes in an OU, Not Sub-OU's

I'm struggling to write a Powershell command that will list all of the mailboxes in an OU, but leave out the mailboxes in sub-OU's.

I've tried:

get-mailbox -OrganizationalUnit "OU=Disabled Accounts,DC=domain,DC=com" | where {$_.distinguishedName -like "CN=*,OU=Disabled*"} | select-object name

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get-mailbox -filter distinguishedName -like "CN=*,OU=Disabled Accounts,DC=domain,DC=COM"

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get-mailbox -OrganizationalUnit "OU=Disabled Accounts,DC=Leavitt,DC=COM" -filter "distinguishedName -like 'CN=*,OU=Disabled Accounts,DC=domain,DC=COM'"

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I'm just not getting this right.  Can someone help?

Thanks,

Dan