大神急急急救救我，感谢感谢

String = """3
   99.5
         asd
             86.6"""

try:
    s = []
    for i in String.split("\n")[1:]:
        a = float(i.strip())
        s.append(a)
    print(f"avg grade ={round(sum(s) / len(s), 2)}\nProcess Completed")
except ValueError:
    for i in String.split("\n")[1:]:
        if max(i) > "9":
            a = i
            break
    print(f"could not convert string to float:'{a.strip()}'")
except ZeroDivisionError:
    print("除数不能为0")