If Then Statements

[mar0000]

data abcd;
input id date encounter;
cards;
1 09APR2012 1
1 11APR2012 1
1 26AUG2012 2
2 10MAY2015 1
2 15AUG2015 2
2 20AUG2015 2
2 02JAN2016 3
2 17MAR2016 4
3 12DEC2013 1
3 18JAN2014 2
4 09SEP2013 1
;
RUN;

I have this dataset that has ID, Date, and encounter. If the dates are within 30 days apart, the encounter remains the same encounter. 

I want to say something like "if the person exists only once and has only one encounter, then newvar = 1"

I also want to say "if the person exists multiple times and only has three or less encounters AND those three encounters occur within the same year (365 days), then newvar2 = 1"

I also want to say "if the person exists multiple times and has three or more encounters AND those encounters occur within mutiple years, then newvar3 = 1"

I'm not entirely sure where to start.

[ChrisNZ]

 So if encounter 1 has dates 10jan2019 and 30 jan2019, and encounter 2 has dates 25jan2020 and 20feb2020, is that still NEWVAR=2 ?

[Kurt_Bremser]

Please fix your data step, so that it creates correct data.