#include <bits/stdc++.h>
using namespace std;
const int INF = INT_MAX;
const long long MOD = 1e9 + 7;
const long long MOD_2 = 998244353;
ifstream fin("test1.txt");
pair<int, int> sum[5000010];
int main() {
  int n;
  cin >> n;
  vector<long long> f(21);
  f[0] = f[1] = 1;
  for (int i = 2; i <= 20; i++) f[i] = f[i - 1] * i;
  long long ans = f[n] / f[n / 2] / f[n / 2];
  ans *= f[n / 2 - 1] * f[n / 2 - 1];
  ans /= 2;
  cout << ans;
}
