package algorithm.baek.recursive;

import algorithm.TestCase;

import java.io.*;

import java.text.ParseException;

public class Hanoi implements TestCase {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

@Override

public void test() throws ParseException, IOException {

int n = Integer.parseInt(br.readLine());

bw.write((int) (Math.pow(2, n) - 1) +"\n");

hanoi(n, 1, 2, 3);

bw.close();

}

private void hanoi(int i, int start, int mid, int to) throws IOException {

if (i == 1) {

bw.write(start + " " + to+"\n");

return;

}

hanoi(i - 1, start, to, mid);

bw.write(start + " " + to+"\n");

hanoi(i - 1, mid, start, to);

}

}