# Another Filling the Grid

## 题目描述

You have $n \times n$ square grid and an integer $k$ . Put an integer in each cell while satisfying the conditions below. - All numbers in the grid should be between $1$ and $k$ inclusive. - Minimum number of the $i$ -th row is $1$ ( $1 \le i \le n$ ). - Minimum number of the $j$ -th column is $1$ ( $1 \le j \le n$ ). Find the number of ways to put integers in the grid. Since the answer can be very large, find the answer modulo $(10^{9} + 7)$ . ![](https://cdn.luogu.com.cn/upload/vjudge_pic/CF1228E/461043b230da4734e02a378fa88336fd5a76ad41.png) These are the examples of valid and invalid grid when $n=k=2$ .

## 输入输出格式

### 输入格式

The only line contains two integers $n$ and $k$ ( $1 \le n \le 250$ , $1 \le k \le 10^{9}$ ).

### 输出格式

Print the answer modulo $(10^{9} + 7)$ .

## 输入输出样例

### 输入样例 #1

2 2


### 输出样例 #1

7


### 输入样例 #2

123 456789


### 输出样例 #2

689974806


## 说明

In the first example, following $7$ cases are possible. ![](https://cdn.luogu.com.cn/upload/vjudge_pic/CF1228E/50e0a56b2ebcb373865c65f252219c6e6fb65791.png)In the second example, make sure you print the answer modulo $(10^{9} + 7)$ .