题目描述
Problem Background
Dear Ling,
Hey, did you know? The speed at which cherry blossoms fall is five centimeters per second.
...So, wait a little longer! In March, at Wuhan University, the cherry blossoms will be here soon.
&sp
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
3 4
1 1 1 1
样例输出
5