我希望我的程序将值“得分”从最高到最低排序

Question

import random #This will import the random function, allowing me to ask the user random questions
import sys #This will allow me to exit the program within the program
score = 0
print ("What is your name?")
name = input()
if name=="" or name==" " or name.isdigit():
    print("Error")
    sys.exit()
print("Hello",name,", are you in class 1,2 or 3?")
print("\nEnter '1' for class 1, enter '2' for class 2 and enter '3' for class     3")
class_name = (input())
if class_name=="" or class_name==" ":
    print("Error")
    sys.exit()

print ('\nYou will be asked 10 questions involving addition, subtraction and multiplicaton')

for x in range(10):#Loop will reapeat 10 times

    operation2 = ['+','-','*']#These are the operations I will use
    operation = random.choice(operation2)#Randomising the operation that will be used
    num1=random.randint(1,10)#Random number 1-10
    num2=random.randint(1,10)#Random number 1-10
    num3=int(eval(str(num1) + operation + str(num2)))

    print ("\n",num1,operation,num2)#Prints the question
    answer=int(input())#User input
    if answer=="" or answer==" ":
        print("Error")
        sys.exit()
    if answer == num3:
        print ("Correct")
        score += 1#Adds 1 to 'score'
    else:
        print("Incorrect")
print("\nYou scored",score,"out of 10") #This will display your final score out of 10

if class_name== '1':
    with open("Class 1 Highest Score.txt", "r") as f:
        lines = f.readlines()
    lines.append("{}:{}\n".format(score,name))
    lines.sort(reverse=True)
    with open("Class 1 Highest Score.txt", "w") as f:
        f.write("".join(lines))

if class_name== '2':
    with open("Class 2 Highest Score.txt", "r") as f:
        lines = f.readlines()
    lines.append("{}:{}\n".format(score,name))
    lines.sort(reverse=True)
    with open("Class 2 Highest Score.txt", "w") as f:
        f.write("".join(lines))

if class_name== '3':
    with open("Class 3 Highest Score.txt", "r") as f:
        lines = f.readlines()
    lines.append("{}:{}\n".format(score,name))
    lines.sort(reverse=True)
    with open("Class 3 Highest Score.txt", "w") as f:
        f.write("".join(lines))

我希望程序将结果输出到有效的文本文件中。然后我希望它按分数从最高到最低排序。它有点工作，基本上如果你在测验中得分10/10，在文本文件中它将10放在底部但除此之外它对它进行了完美排序，但我将如何解决这个问题。

提前感谢：）