import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.TreeMap;
import java.util.TreeSet;

import static java.util.Comparator.*;

public class Main {
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        Solver solver = new Solver(System.in, out);
        solver.solve();
        out.close();
    }
}
class Solver {
	Scanner sc;
	PrintWriter out;
    public Solver(InputStream in, PrintWriter out) {
    	sc = new Scanner(in);
    	this.out = out;
    }
    // ==================================================================
    int N;
    long calc(int now, int l, int r) {
//    	out.println("開始　：　now = " + now + "  l = " + l + "  r = " + r);
    	if(now == 2 * N) {
    		if(l == r)	return 1;
    		else		return 0;
    	}
    	if(l < r || l > N || r > N)		return 0;
    	long ans = calc(now + 1, l + 1, r);
    	ans += calc(now + 1, l, r + 1);
//    	out.println("終了　：　now = " + now + "  l = " + l + "  r = " + r + "  --> ans = " + ans);
    	return ans;
    }
    public void solve() {
    	N = Integer.parseInt(sc.next());
    	out.println(calc(0, 0, 0));
    }    
    // ==================================================================
}