import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		sc.close();

		int end = n * 2 - 1;
		List<List<Integer>> list = new ArrayList<>(end);
		for (int i = 0; i < end; i++) {
			list.add(new ArrayList<>(n));
		}

		for (int i = end; i > n; i--) {
			for (int j = 0; j < i; j++) {
				list.get(j).add(i);
			}
		}
		for (int i = 1; i <= n; i++) {
			list.get(i - 1).add(i);
		}
		for (int i = n; i > 0; i--) {
			for (int j = end - i + 1; j < end; j++) {
				list.get(j).add(i);
			}
		}

		System.out.println(end);
		for (int i = 0; i < end; i++) {
			StringBuilder sb = new StringBuilder();
			for (int e : list.get(i)) {
				sb.append(e).append(' ');
			}
			sb.deleteCharAt(sb.length() - 1);
			System.out.println(sb.toString());
		}
	}
}