1 #include <iostream>
 2 #include<stdio.h>
 3 #include<string.h>
 4 #include<string>
 5 #include<algorithm>
 6 #define ll long long
 7 using namespace std;
 8 #define N 100
 9 ll dp[40];
10 
11 int main()
12 {
13     ll n;
14     dp[1]=1ll;
15       dp[2]=2ll;
16       for(int i=3;i<=27;i++){
17         dp[i]=2ll*(2ll*i-1ll)*dp[i-1]/(i+1ll);
18       }
19 
20     while(scanf("%lld",&n)!=EOF){
21       printf("%lld\n",dp[n-2]);
22     }
23 
24     return 0;
25 }