How can I create this program in python?

The program should allow the tutor to enter in the various marks awarded, until the tutor enters in a negative mark (e.g., -1).

When a negative mark is entered, the program should display a histogram where each star represents a student who achieved a module mark in the category range:

 - 0-29   
 - 30-39
 - 40-69
 - 70-100

This example shows the output distribution for 20 marks.

 - 0-29 ***   
 - 30-39 ***** 
 - 40-69 ******** 
 - 70-100 **** 

20 students in total.