Codeforces Round 745 (Div. 1)
B
Mathematics Curriculum
Codeforces
2600
原题
← AC →
翻译中…

Let $c_1, c_2, \ldots, c_n$ be a permutation of integers $1, 2, \ldots, n$. Consider all subsegments of this permutation containing an integer $x$. Given an integer $m$, we call the integer $x$ good if there are exactly $m$ different values of maximum on these subsegments.

翻译中…

Cirno is studying mathematics, and the teacher asks her to count the number of permutations of length $n$ with exactly $k$ good numbers.

翻译中…

Unfortunately, Cirno isn't good at mathematics, and she can't answer this question. Therefore, she asks you for help.

翻译中…

Since the answer may be very big, you only need to tell her the number of permutations modulo $p$.

翻译中…

A permutation is an array consisting of $n$ distinct integers from $1$ to $n$ in arbitrary order. For example, $[2,3,1,5,4]$ is a permutation, but $[1,2,2]$ is not a permutation ($2$ appears twice in the array) and $[1,3,4]$ is also not a permutation ($n=3$ but there is $4$ in the array).

翻译中…

A sequence $a$ is a subsegment of a sequence $b$ if $a$ can be obtained from $b$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.

翻译中…

Input

翻译中…

The first line contains four integers $n, m, k, p$ ($1 \le n \le 100, 1 \le m \le n, 1 \le k \le n, 1 \le p \le 10^9$).

翻译中…

Output

翻译中…

Output the number of permutations modulo $p$.

翻译中…

Note

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In the first test case, there are four permutations: $[1, 3, 2, 4]$, $[2, 3, 1, 4]$, $[4, 1, 3, 2]$ and $[4, 2, 3, 1]$.

翻译中…

Take permutation $[1, 3, 2, 4]$ as an example:

翻译中…

For number $1$, all subsegments containing it are: $[1]$, $[1, 3]$, $[1, 3, 2]$ and $[1, 3, 2, 4]$, and there're three different maxima $1$, $3$ and $4$.

翻译中…

Similarly, for number $3$, there're two different maxima $3$ and $4$. For number $2$, there're three different maxima $2$, $3$ and $4$. And for number $4$, there're only one, that is $4$ itself.

翻译中…

样例

Input #1
4 3 2 10007
Output #1
4
InputCopy OutputCopy
Input #2
6 4 1 769626776
Output #2
472
InputCopy OutputCopy
Input #3
66 11 9 786747482
Output #3
206331312
InputCopy OutputCopy
Input #4
99 30 18 650457567
Output #4
77365367
InputCopy OutputCopy
题目信息
题号
1580B
时间限制
2 s
内存限制
256 MB
标签
暴力
组合数学
动态规划
树

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