var
 stroka:string;
 i, max, tmp:integer;
begin
read(stroka);
max:=0;
tmp:=0;
for i:=1 to length(stroka)do begin
 if  stroka[i]='a' then tmp:=tmp+1 else begin
   if tmp>max then max:=tmp;
   tmp:=0;
 end;
end;
writeln(max);
end.