How to get month start date and enddate based on number of weeks

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1

i am trying to get start date and end date for my calender table for which the number of weeks will differ
jan-4 weeks
feb-4 weeks
mar-5 weeks

2

what does your calendar table look like? if you could post sample data

3

my calender is a 4-4-5 calender
jan- 4 weeks(i.e month start date will be 1 jan and end date will be 28-jan)
feb -4 weeks (i.e month start date will be 29 th jan and end date will be 25-feb)
march-5 weeks(i.e month start date will be 26th feb and end date will be 02-apr)
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can u plse reply me as soon as possible i am using sql plus editor