#include <bits/stdc++.h> using namespace std; unsigned long long jiecheng(unsigned long long jc) { if (jc == 0) return 1; return jiecheng(jc-1) * jc; } unsigned long long CTLS(unsigned long long n) {// h n+1 if (n<=0) return 1; // int h = n-1; unsigned long long tmp = jiecheng(n); // cout << jiecheng(2*n) << endl; return jiecheng(2*n)/(tmp * tmp*(n+1)); } int main() { unsigned long long n, ans = 0; cin >> n; cout << CTLS(n-2); return 0; }