Elena_string

var
st:string; s,m,i:integer;
begin
     write('Vvedi stroku: ');
     readln(st);
     m:=0;
     for i:=1 to length(st) do
         if st[i]='a' then
         begin
            s:=0;
            while(st[i]='a')do
              begin
              s:=s+1;
              i:=i+1;
              end;
            if m<s then
               m:=s;
            i:=i-1;
         end;
     writeln(m);
     readln;
end.