#include <bits/stdc++.h> #define int long long using namespace std; int c[105]; int n; signed main() { cin >> n; c[2] = 1; for (int i = 3; i <= n; i++) for (int j = 2; j < i; j++) c[i] += c[j] * c[i + 1 - j]; printf("%lld\n",c[n]); return 0; }