#include<bits/stdc++.h> using namespace std; long ling n , f[30] = {1,1,2} ; int main() { for(int i = 3 ; i <= 25 ; i++) { for(int j = 0 ; j <= i-1 ; j++) { f[i]+=f[j]*f[i-j-1] ; } } while(cin >> n) { cout << f[n]<<endl; } return 0 ; }