#include <bits/stdc++.h> using namespace std; long long dp[35]; int main(){ dp[0] = 1; dp[1] = 1; dp[2] = 2; for(int i = 3;i<=25;i++){ for(int j = 0;j<=i;j++){ dp[i]+=dp[j]*dp[i-j-1]; } } int n; while(cin>>n)cout<<dp[n]<<endl; return 0; }