#include <bits/stdc++.h>
using namespace std;

#define INF 100000000
#define YJ 1145141919
#define INF_INT_MAX 2147483647
#define INF_LL 9223372036854775
#define INF_LL_MAX 9223372036854775807
#define EPS 1e-10
#define MOD 998244353
#define MOD9 998244353
#define Pi acos(-1)
#define LL long long
#define ULL unsigned long long
#define LD long double

#define int long long

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(a)  begin((a)), end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())

const int MAX_N = 50;

int N;
int dp[MAX_N][MAX_N];

signed main()
{
  cin >> N;
  dp[0][0] = 1;

  REP(n,2*N) {
    REP(m1,N+1) {
      int m2 = n - m1;
      if(m1+1 <= N) {
        dp[n+1][m1+1] += dp[n][m1];
      }
      if(m2+1 <= N && m1 >= m2+1) {
        dp[n+1][m1] += dp[n][m1];
      }
    }
  }

  cout << dp[2*N][N] << endl;

  return 0;
}