import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {

	public static void main(String[] args) {
		new Main().run();
	}
	
	long comb(long n,long k) {
		long ret=1;
		for(long i=n;i>=n-k+1;--i)ret*=i;
		for(long i=1;i<=k;++i)ret/=i;
		return ret;
	}
	
	void run() {
		Scanner sc = new Scanner(System.in);
		long n=sc.nextLong();
		System.out.println(comb(2*n,n)-comb(2*n,n-1));
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}