#include <bits/stdc++.h>
using namespace std;
long long A[50];
int main() {
  long long n;
  A[0] = A[1] = 1;
  scanf("%lld", &n);
  for (long long i = 1; i <= 50; ++i) {
    A[i] = A[i - 1] * i;
  }
  long long ans = A[n] / A[n / 2] / A[n / 2] / 2;
  ans *= A[n / 2 - 1] * A[n / 2 - 1];
  printf("%lld", ans);
  return 0;
}
