键盘输入一组学生成绩，输入以-1作为输入的结束。统计这批数据的最大值，最小值，平均值

```python

初始化变量

scores = []

max_score = None

min_score = None

输入循环

while True:

try:

if score == -1:

break

scores.append(score)

if max_score is None or score > max_score:

max_score = score

if min_score is None or score < min_score:

min_score = score

except ValueError:

print("输入无效，请输入一个数字。")

计算平均值

if scores:

average_score = sum(scores) / len(scores)

else:

average_score = 0

输出结果

print(f"最大值：{max_score