Flag rows with 3 consecutive months -1 or 2 days of gap is allowed

[SAS03]

Hello,

I have a dataset like this :

ID	date	days
ID1	02/03/2017	28
ID1	30/03/2017	30
ID1	01/05/2017	7
ID1	10/05/2017	90
ID2	24/12/2018	14
ID2	09/01/2019	56
ID2	06/03/2019	20

I want to add a flag which will take 1 if there is 3 consecutive months (90 days) by ID -a gap of 1 or 2 days is allowed- otherwise will take 0 :

ID	date	days	end_date	flag
ID1	02/03/2017	28	30/03/2017	0
ID1	30/03/2017	30	29/04/2017	0
ID1	01/05/2017	7	08/05/2017	0
ID1	10/05/2017	90	08/08/2017	1
ID2	24/12/2018	14	07/01/2019	1
ID2	09/01/2019	56	06/03/2019	1
ID2	06/03/2019	20	26/03/2019	1

[Ksharp]

Why not the third obs take flag=1 ? since the gap is only two days .

[SAS03]

The sum days of the 3 first rows is 65days < 90 days, that's why the third row will have 0 and not 1

[Ksharp]

Then the second obs ? since the gap is only two days . 29/04/2017 --> 01/05/2017