import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long[][] dp = new long[n + 1][n + 1];
        dp[n][n] = 1;
        for (int i = 1; i <= 2 * n; i++) {
            int right;
            int left;
            if (i > n) {
                right = 2 * n - i;
                left = 0;
            } else {
                right = n;
                left = n - i;
            }
            while (left <= right) {
                if (left < n) {
                    dp[left][right] += dp[left + 1][right];
                }
                if (right < n) {
                    dp[left][right] += dp[left][right + 1];
                }
                left++;
                right--;
            }
        }
        System.out.println(dp[0][0]);
    }
}