Unless otherwise provided in the law, holidays and weekly off days coming during the leave period would be treated as leave only. Therefore, if there are holidays and weekly off days during this 20 days, the same would be marked as leave only and you can not compensate the same by another day or your number of leaves would not reduce by these holidays or weekly off days.
Under Factories Act (it is a Central Act which applies to all states), however, it is specifically provided that holidays and weekly off days intervening leave periods should not be counted as leaves. Please remember that it applies to the earned leaves only.