#include <bits/stdc++.h>
long long expo(long long x, long long y) {
  long long res = 1;
  while (y) {
    if (y % 2) res = (res * x % 1000000007) % 1000000007;
    x = (x * x) % 1000000007;
    y /= 2;
  }
  return res;
}
using namespace std;
long long factorial(long long n) {
  return (n == 1 || n == 0) ? 1 : n * factorial(n - 1);
}
void solve() {
  long long n;
  cin >> n;
  cout << factorial(n - 1) / (n / 2) << endl;
}
signed main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  { solve(); }
  return 0;
}
