python算数题

import random
print("-- -- -- -- 口算大师 -- -- -- --")
while True:
    coin = random.randint(1,4)
    a=random.randint(0,10)
    b=random.randint(0,10)
   
    if coin == 1:        
        c=a+b
        user = input(str(a)+" + "+str(b)+" = ")
    elif coin == 2:
        c=a-b
        user = input(str(a)+" - "+str(b)+" = ")
    elif coin == 3:
        c=a*b
        user = input(str(a)+"*"+str(b)+"=")
    elif coin == 4:
        b=random.randint(1,10)
        c=round(a/b,2)
        user = input(str(a)+"/"+str(b)+"=（保留两位小数，整除+.0）")
        
    if str(c) == user:
        print("你有点“牛”")
    else:
        print("你不会是小蠢材电话手表带多了吧")