#include <bits/stdc++.h>
using namespace std;
const long long Maxn = 1e2 + 5;
long long n, mul[Maxn];
int main() {
  scanf("%lld", &n);
  mul[0] = 1;
  for (long long i = 1; i <= n; i++) mul[i] = 1ll * mul[i - 1] * i;
  printf("%lld\n", mul[n] / mul[n / 2] / mul[n / 2] / 2 * mul[n / 2 - 1] *
                       mul[n / 2 - 1]);
  return 0;
}
