Figure out whether the price has been higher than Donchain TOP in the last 20 periods

Hey guys

So if I want to check whether CCI has been higher than 300 in the last 20 periods I do this:

 bool cci300_10 = _cci.Result.Maximum(10) >= 300;

...but what in case I would like to figure out whether the price has been higher than Donchain TOP in the last 20 periods?

bool dncTOP = MarketSeries.High.Maximum(20) >= _dnc50.Top.Last(0);

?

I'm not sure this code will work since it compares it with with the value of the last period...

Any ideas?