# Team Work

## 题目描述

You have a team of $N$ people. For a particular task, you can pick any non-empty subset of people. The cost of having $x$ people for the task is $x^{k}$ . Output the sum of costs over all non-empty subsets of people.

## 输入输出格式

### 输入格式

Only line of input contains two integers $N$ $(1<=N<=10^{9})$ representing total number of people and $k$ $(1<=k<=5000)$ .

### 输出格式

Output the sum of costs for all non empty subsets modulo $10^{9}+7$ .

## 输入输出样例

### 输入样例 #1

1 1


### 输出样例 #1

1


### 输入样例 #2

3 2


### 输出样例 #2

24


## 说明

In the first example, there is only one non-empty subset ${1}$ with cost $1^{1}=1$ . In the second example, there are seven non-empty subsets. \- ${1}$ with cost $1^{2}=1$ \- ${2}$ with cost $1^{2}=1$ \- ${1,2}$ with cost $2^{2}=4$ \- ${3}$ with cost $1^{2}=1$ \- ${1,3}$ with cost $2^{2}=4$ \- ${2,3}$ with cost $2^{2}=4$ \- ${1,2,3}$ with cost $3^{2}=9$ The total cost is $1+1+4+1+4+4+9=24$ .