var fs = require('fs');
//var input = fs.readFileSync('/dev/stdin').toString().split('');
var input = fs.readFileSync('test.text').toString()

function solution(input) {
    console.log(Math.pow(2, input) - 1)
    if (input <= 20) {
        hanoi(input, 1, 2, 3)
    }
}

function hanoi(n, fr, others, to) {
    if (n === 1) {
        console.log(fr, to)
        return
    }

    hanoi(n - 1, fr, to, others)
    console.log(fr, to)
    hanoi(n - 1, others, fr, to)
}

solution(input)