Words with 23 syllables are stressed on the initial syllable; those with 4 are stressed on the first and third; and those with 5 or more on the antepenultimate (third-last).
Syllable stress is penultimate unless the penultimate syllable is light and the antepenultimate syllable is heavy, in which case stress is on the antepenultimate.
In words of three or more syllables, the stress is on the penultimate syllable if this is heavy, otherwise on the antepenultimate syllable, i.e. the third-to-last syllable.