#include <bits/stdc++.h>
using namespace std;
long long f[21];
clock_t startTime;
double getCurrentTime() {
  return (double)(clock() - startTime) / CLOCKS_PER_SEC;
}
int main() {
  startTime = clock();
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  f[0] = 1;
  f[1] = 1;
  for (int i = 2; i < 21; ++i) {
    f[i] = i * f[i - 1];
  }
  long long n;
  cin >> n;
  long long ncr = f[n] / (f[n / 2] * f[n / 2]);
  ncr /= 2;
  long long xx = f[n / 2 - 1] * f[n / 2 - 1];
  long long s = ncr * xx;
  cout << s << "\n";
  cerr << getCurrentTime();
  return 0;
}
