#include <bits/stdc++.h>
using namespace std;
const unsigned int MOD = 1000000007;
void matter() {
  long long n;
  long long ans = 1, f;
  cin >> n;
  for (int i = 1; i < n + 1; i++) {
    ans = ans * i;
  }
  ans = (ans * 2);
  ans = ans / (n * n);
  cout << ans;
}
int main(void) {
  long long tc = 1;
  while (tc--) {
    matter();
  }
  return 0;
}
