var n,i: integer;
    a: array[1..1000] of integer;
    check: boolean;
begin
    readln(n);
    for i:=1 to n do read(a[i]);
    check:=true;
    for i:=1 to n div 2 do if a[i]<>a[n-i+1] then begin
        check:=false;
        break;
    end;
    if check then write('Day tren doi xung') else write('Day tren khong doi xung')
end.