Type: Default 1000ms 64MiB

核电站

You cannot submit for this problem because the contest is ended. You can click "Open in Problem Set" to view this problem in normal mode.

Description

一个核电站有n个放核物质的坑,排列在一条直线上。如果连续m个坑中放入核物质就会发生爆炸,所以某些坑中就不能放核物质。

本题的任务是:对于给定的n和m,求不发生爆炸的放置核物质的方案总数。

Format

Input

一行两个正整数n和m,之间用一个空格隔开,2≤n≤50,2≤m≤5。

Output

一行一个正整数,表示方案总数。

Samples

4 3
13

Limitation

1s, 64MB for each test case.

周六10:30

Not Attended
Status
Done
Rule
ACM/ICPC
Problem
11
Start at
2023-12-9 10:00
End at
2023-12-9 12:00
Duration
2 hour(s)
Host
Partic.
2