Challenge: The program below doesn't run well find and fix the error

Question

# save this as a *.py file (the * is a variable for any text)

max = int(input("How much courses: "))

courses = []
units = []
grades = []
total = []

grades_notes = {
'A': 5,
'a': 5,
'B': 4,
'b': 4,
'C': 3,
'c': 3,
'D': 2,
'd': 2,
'F': 1,
'f': 1,
}

for i in range(max):
print(i+1, ". course: ", end="", sep="")
courses.append(input())
print(i+1, ". unit: ", end="", sep="")
units.append(input())
print(i+1, ". grade: ", end="", sep="")
grades.app

Answer 1

What's is the problem exactly?
After studying it to understand what was expected as user entry, and give it correct values, he seem's to be ok ^^

Answer 2

rest of the code.

grades.append(input())
print()

for i in range(max):
a = int(units[i]) * int(grades_notes[grades[i]])
print(i, ". course: ", courses[i], ": ", a, sep="")
total.append(a)

a = 0

for i in range(len(total)):
a += total[i]

print("Total: ", a/len(total), sep="")