#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cout << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  long long n;
  cin >> n;
  long long ans = 1;
  for (long long i = 3; i <= n; i++) ans *= i;
  ans /= (n / 2) * (n / 2);
  cout << ans;
  return 0;
}
