program Belozor7 var f1 f2 text res integer string begin assign f1 inp

program Belozor7;
 var f1,f2:text;
   res,n, i:integer;
   a:string;

begin
  assign(f1, 'input.txt');
   assign (f2,'output.txt');
   reset(f1);
   rewrite(f2);
    read(f1,a);
   for i :=0 to 255 do begin
   if a[i]='a' then inc (n)
   else begin
  if res<n then res:=n;
  n:=0
  end;
   end ;
   write(f2,res);
   close (f1);
   close(f2);
end.