Hi Cindia,
If you create a smart list for reporting, you can edit the default view and add the field "SFDC ID" to be displayed in your smart list results.
You can edit the default view by clicking on the "View: default" button above the smart list results.
![0EM50000000RwGN.jpg 0EM50000000RwGN.jpg](/t5/image/serverpage/image-id/14802i64548845DA9737E3/image-size/large?v=v2&px=999)
From there just select "SFDC ID" as a field that you would like to appear and then you will be able to export those results using the export to Excel button at the bottom of the smart list.
This should provide you with the lead/contact IDs so you can compare with reports generated in Salesforce.
Hope this helps,
Nate