if marks > TotalMarks: TypeError: '>' not supported between instances of 'list' and 'int'

helping my cousin fix some code, trying to figure out if its in this part of the code, something i need to fix the error. he's trying to make the code where it says:

heres the error

    while total_marks < marks:
TypeError: '<' not supported between instances of 'int' and 'list'

    while total_marks < marks:
        print('Invalid entry')
        marks = len(input('Re-enter the mark'))
    marks.append(marks)

is where the error is I think.

# Question 6
def q6():
    print("This is question 6!!!\n")
    print("Student grades\n")
    num_students = int(input("How many students would you like to enter?"))
    total_marks = int(input("What is the total number of marks a student can get?"))
    names = []
    marks = []
    for i in range(num_students):
        names.append(input("Name"))
        marks.append(int(input("grade")))

    while total_marks < marks:
        print('Invalid entry')
        marks = len(input('Re-enter the mark'))
    marks.append(marks)

    percent: int[Any] = []
    for i in range(len(marks)):
        percent.append(marks[i] / total_marks * 100)

    grade = []
    for i in range(len(percent)):
        if 90 <= percent <= 100:
            grade.append("H1")
        elif 80 <= percent <= 89:
            grade.append("H2")
        elif 70 <= percent <= 79:
            grade.append("H3")
        elif 60 <= percent <= 69:
            grade.append("H4")
        elif 50 <= percent <= 59:
            grade.append("H5")
        elif 40 <= percent <= 49:
            grade.append("H6")
        elif 30 <= percent <= 39:
            grade.append("H7")
        elif 0 <= percent <= 29:
            grade.append("H8")
    for i in range(num_students):
        print(names[i])