#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18 + 5;
const long long MOD = 1000000007;
void solve() {
  long long n;
  cin >> n;
  vector<long long> f(n + 1);
  f[0] = 1;
  for (long long i = 1; i <= n; ++i) {
    f[i] = i * f[i - 1];
  }
  long long ans = f[n] / f[n / 2] / f[n / 2];
  ans *= f[n / 2 - 1];
  ans *= f[n / 2 - 1];
  ans /= 2;
  cout << ans << "\n";
}
signed main() {
  cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
  long long T = 1;
  while (T--) {
    solve();
  }
  return 0;
}
