As has been explained more than once to retards like you, it works like this.
MONTH = a number from 1 to 12, inclusive.
DAY = a number from 1 to 31, inclusive.
YEAR = Currently a number of 2019, increases.
The numbers are in ascending order of the HIGHEST possible number. 12 will never be higher than 31, so MONTH is first. 31 is never going to be HIGHER than 2019, so it comes second. Finally, YEAR.
It's not goddamned rocket science, you pathetic twat.
Now, stop asking these, and other, retard questions.