B. Permutation
A permutation p is an ordered group of numbers p1, p2, ..., pn, consisting of n distinct positive integers, each is no more than n. We'll define number n as the length of permutation p1, p2, ..., pn.
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: 
.
Output
Print 2n integers a1, a2, ..., a2n — the required permutation a. It is guaranteed that the solution exists. If there are multiple solutions, you can print any of them.
Note
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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#include <iostream>
using namespace std;
int n,k;
int a[50010];
void Read()
{
cin>>n>>k;
int d = n*2 - 2*k;
for ( int i = 1;i<=d; i+=2)
{
cout<<i+1<<" "<<i<<" ";
}
d++;
n= n*2;
for ( int i = d; i<=n;i++)
cout<<" "<<i;
}
int main()
{
Read();
}