Query capture

Hi,

I want to capture those queries on basis of following criteria.

1)SQLs that take more than 5 seconds
2)SQLs that take more than 10 seconds
3)SQLs that take more than 20 seconds

Can I do it without explain plan?
I want to set up script which will capture only those query which are taking more than 5,10,20 minutes to execute whether the table is small or large. thanks

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