N=int(input())

dp=[[0 for i in range(27)]for j in range(27)]
dp[1][1]=1
for i in range(2,27):
    for j in range(1,27):
        dp[i][j]+=dp[i-1][j-1]
        dp[i][j]+=dp[i-1][j]
        if (i/2)>j:
            dp[i][j]=0
print(dp[N*2][N])