Например,
INPUT: CBA
OUTPUT: ABC .
var s:string;
i,j:byte;
c:char;
begin
readln(s);
for i:=1 to length(s)-1 do
for j:=i+1 to length(s) do
if s[i]>s[j] then
begin
c:=s[i];
s[i]:=s[j];
s[j]:=c;
end;
writeln(s);
end;