int Nprint(int n)
{
unsigned int i = 1;
unsigned int N = n - 1;
while (i < 2*n)
{
if (i <= n) std::cout << i << " ";
else std::cout << N-- << " ";
i++;
}
return 0;
}
int main()
{
int n = 0;
std::cout << "";
std:: cin >> n;
Nprint(n);
std::cout << std::endl;
return 0;
}