#include <iostream>
using namespace std;
int main()
{
int n, prod = 1;
cin >> n;
for (int i = 3 ; i <= n; i+= 2)
prod *= i;
cout << prod;
return 0;
}
#include <iostream>
using namespace std;
int main()
{
int n, prod = 1;
cin >> n;
for (int i = 3 ; i <= n; i+= 2)
prod *= i;
cout << prod;
return 0;
}