#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1e9 + 7;
long long int mod(long long int x) { return (x % MOD + MOD) % MOD; }
const long long int first = 21;
long long int f[first];
void solve() {
  long long int n;
  cin >> n;
  f[0] = 1;
  for (long long int i = 1; i < first; i++) {
    f[i] = f[i - 1] * i;
  }
  long long int ans = f[n] / (f[n / 2]) / f[n / 2];
  ans = ans * f[n / 2 - 1] * f[n / 2 - 1];
  ans /= 2;
  cout << ans << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
