#include <iostream>
using namespace std;

int main()
{
  int n;
  cout<<"Compter jusqu'a? ";
  cin>>n;
  for (int j = 1; j <= n; ++j)
  {
    cout<<j<<" ";
  }
  for (int j = n; j >= 1; --j)
  {
    cout<<j<<" ";
  }
  cout<<endl;
}
