CF359B.Permutation

普及/提高-

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题目描述

A permutation $p$ is an ordered group of numbers $p_{1},p_{2},...,p_{n}$ , consisting of $n$ distinct positive integers, each is no more than $n$ . We'll define number $n$ as the length of permutation $p_{1},p_{2},...,p_{n}$ .

Simon has a positive integer $n$ and a non-negative integer $k$ , such that $2k<=n$ . Help him find permutation $a$ of length $2n$ , such that it meets this equation: .

输入格式

The first line contains two integers $n$ and $k$ ( $1<=n<=50000$ , $0<=2k<=n$ ).

输出格式

Print $2n$ integers $a_{1},a_{2},...,a_{2n}$ — the required permutation $a$ . It is guaranteed that the solution exists. If there are multiple solutions, you can print any of them.

输入输出样例

输入#1
```
1 0
```
输出#1
```
1 2
```
输入#2
```
2 1
```
输出#2
```
3 2 1 4
```
输入#3
```
4 0
```
输出#3
```
2 7 4 6 1 3 5 8
```

说明/提示

Record $|x|$ represents the absolute value of number $x$ .

In the first sample $|1-2|-|1-2|=0$ .

In the second sample $|3-2|+|1-4|-|3-2+1-4|=1+3-2=2$ .

In the third sample $|2-7|+|4-6|+|1-3|+|5-8|-|2-7+4-6+1-3+5-8|=12-12=0$ .

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