If you were the Principal, what would you do with students that are constantly late to School? Class?

If you were the Principal, what would you do with students that are constantly late to School? Class?

If I was the principal and my students are constantly late to i wouldn't do nothing because they are young adults and they are going to keep doing what they want to do. But If they are going to class late everyday without and excuse then it's a problem. They would get detention for the first time then if they are late to class again without an excuse they will be suspended from school.