#include <bits/stdc++.h>
using namespace std;
void c_p_c() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
long long fac(long long i) {
  if (i == 0) {
    return (long long)(1);
  } else {
    return (long long)(i * fac(i - 1));
  }
}
void solve() {
  long long n = 0;
  cin >> n;
  n /= 2;
  n--;
  long long ans = fac((2 * n) + 1);
  ans /= (n + 1);
  cout << ans << endl;
}
int main() {
  c_p_c();
  solve();
  return 0;
}
