how to remove mulitple word

[Aayushi_17]

if i have input as 'aaaaaabbbbcccccccc' then  output should be populated with single value like 'abc'.

Thanks in advance

[PeterClemmensen]

What if it was "aaaaaabbbbccccccccaaaaaaa" ?

[Aayushi_17]

yes order can be different

[PeterClemmensen]

But would the string I posted result in "abc" or "abca" ?

[Aayushi_17]

it should be abc no mulitple a can be used 

[PeterClemmensen · Accepted solution]

Ok try this

data _null_;
   s1 = "aaaaaabbbbcccccccc";
   s2 = prxchange("s/(.)(?=\1{1})//", -1, s1);
   put s2=;
run;