program filip;
var brs, a, b : string[7];
    i : integer;

begin
    readln(brs);

    for i := 7 downto 5 do begin
        a := a + brs[i];
        b := b + brs[i-4];
    end;

    if a > b then
        writeln(a)
    else
        writeln(b);
end.