need to split first 2 nums of same id by 2

[vraj1]

data have;
infile datalines dsd truncover;
input id num (start end) (:date9.);
format start end date9.;
datalines4;
101,2,12MAR2018,18MAR2018
101,3,15MAR2018,19MAR2018
101,4,20MAR2018,29MAR2018
102,2,12JAN2018,19JAN2018
102,3,20JAN2018,28JAN2018
102,4,29JAN2018,12FEB2018
102,5,13FEB2018,18FEB2018
102,6,19FEB2018,28FEB2018
;;;;
run;

data want;
infile datalines dsd truncover;
input id num (start end) (:date9.);
format start end date9.;
datalines4;
101,2,12MAR2018,13MAR2018
101,2,14MAR2018,15MAR2018
101,2,16MAR2018,18MAR2018
101,3,15MAR2018,19MAR2018
101,4,20MAR2018,29MAR2018
102,2,12JAN2018,19JAN2018
102,3,20JAN2018,28JAN2018
102,4,29JAN2018,12FEB2018
102,5,13FEB2018,18FEB2018
102,6,19FEB2018,28FEB2018
;;;;
run;

I need to split first nums with 2 days duration for 2 times as shown in want. any suggestion? if the total duration is less than 4 then it should split in num3 for all id's.

[ChrisNZ]

Why is 101,2 the only record split?

[vraj1]

data have;
infile datalines dsd truncover;
input id num (start end) (:date9.);
format start end date9.;
datalines4;
101,2,12MAR2018,13MAR2018
101,3,16MAR2018,19MAR2018
101,4,20MAR2018,29MAR2018
102,2,12JAN2018,19JAN2018
102,3,20JAN2018,28JAN2018
102,4,29JAN2018,12FEB2018
102,5,13FEB2018,18FEB2018
102,6,19FEB2018,28FEB2018
;;;;
run;

data need;
 set have;
 by id num;
 retain end1;
 format end1 date9.;
 If first.id then do;
 do i=1 to 3;
 if i=1 then do; start=start; end1=start+1; output; end;
 if i=2 then do; start=end1+1; end1=start+1; output; end;
 if i=3 then do; start=end1+1; end1=end;output; end;
If end1=end then i =4;
 end;
 end;
Else do;
End1=end; output; end;
run;

i used the below code but it somehow doesnt split if the first num doesnt have enough duration