#include <iostream>

using namespace std;

int n, f[][];

int main()

{

    cin >> n;

    for (int i=;i<=n;i++)

        f[i][] = f[][i] = ;

    for (int i = ; i <= n; i ++)

        for (int j = ; j <= n; j ++)

            f[i][j] = f[i-][j] + f[i][j-];

    cout << f[n][n];

    return ;

}