输入正整数n，计算1~n所有偶数的和

状态	递交者	时间	内存	语言	代码	递交时间
AC	abc	50ms	10.4 MiB	Python 3	48 Bytes	2025-5-6 16:57:02
AC	pwp	51ms	10.4 MiB	Python 3	69 Bytes	2025-4-21 9:23:50
AC	yiyinglian	52ms	10.4 MiB	Python	69 Bytes	2025-4-22 16:49:42
AC	wxw2	53ms	10.3 MiB	Python 3	69 Bytes	2025-4-21 15:54:23
AC	Urplues	54ms	10.4 MiB	Python 3	90 Bytes	2025-5-6 17:08:51
AC	zhangjiangping	56ms	10.4 MiB	Python	70 Bytes	2025-4-21 16:09:03
AC	友人A	59ms	10.4 MiB	Python 3	96 Bytes	2025-5-6 16:56:56
AC	tianmongda	59ms	10.4 MiB	Python 3	69 Bytes	2025-4-22 16:52:42
AC	zhiqi	59ms	10.2 MiB	Python 3	70 Bytes	2025-4-22 16:53:44