解题思路

使用编程小组集合减去篮球小组集合。

n, m = map(int, input().split())
programming = set(map(int, input().split()))
basketball = set(map(int, input().split()))

result = sorted(programming - basketball)

print(len(result))

if len(result) == 0:
    print("NONE")
else:
    print(*result)