#include <vector>
#include <iostream>

using namespace std;

int main(int argc, char * argv[])
{
    const int N = 10;

    vector<int> a(2*N);
    for(int i = 0; i < 2*N; ++i) a[i] = i+1;

    for(int i = 0; i < 2*N; ++i) cout << a[i] << " "; cout << "\n";

    for(int i = N; i <= 2*N-2; ++i)
    {
        for(int j = 0, k = i; j < 2*N-i-1; ++j,--k)
        {
            swap(a[k],a[k-1]);
        }
    }

    for(int i = 0; i < 2*N; ++i) cout << a[i] << " "; cout << "\n";
}