Codeforces_509A

// Codeforces 509A

#include <iostream>

using namespace std;

int main()
{
    int n, maxim = 0;
    cin >> n;
    int nn[n][n];
    for( int i = 0; i < n; i++ )
    {
        for( int y = 0; y < n; y++ )
        {
            if( i == 0 || y == 0 )
            {
                nn[i][y] = 1;
            }
            else
            {
                nn[i][y] = nn[i-1][y] + nn[i][y-1];
            }
            if( nn[i][y] > maxim ){ maxim = nn[i][y]; }
        }
    }
    cout << maxim;
    return 0;
}