#![allow(unused_imports)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;
use std::ops::Bound::*;

#[allow(unused_macros)]
macro_rules! debug {
    ($($e:expr),*) => {
        #[cfg(debug_assertions)]
        $({
            let (e, mut err) = (stringify!($e), std::io::stderr());
            writeln!(err, "{} = {:?}", e, $e).unwrap()
        })*
    };
}

fn main() {
    let n = read::<usize>();
    let mut counts = (0..=2 * n - 1).collect::<Vec<_>>();
    counts[2 * n - 1] -= 2;
    counts[2 * n - 2] -= 2;
    counts[2 * n - 3] -= 2;
    let mut answers = vec![
        (2 * n - 3, 2 * n - 2, 2 * n - 1),
        (2 * n - 3, 2 * n - 2, 2 * n - 1),
    ];

    debug!(counts);

    let mut p1 = 1;
    'outer: while p1 < n {
        let mut uppers = (n..=2 * n - 1).map(|x| (counts[x], x)).collect::<Vec<_>>();
        uppers.sort();
        uppers.reverse();

        for i in 0..uppers.len() {
            if counts[uppers[i].1] == 0 {
                continue;
            }
            for j in i + 1..uppers.len() {
                if counts[uppers[j].1] == 0 {
                    continue;
                }
                answers.push((p1, uppers[i].1, uppers[j].1));
                counts[p1] -= 1;
                counts[uppers[i].1] -= 1;
                counts[uppers[j].1] -= 1;
                if counts[p1] == 0 {
                    p1 += 1;
                    continue 'outer;
                }
            }
        }
        p1 += 1;
    }
    debug!(counts);

    println!("{}", answers.len());
    for (i, j, k) in answers {
        println!("{} {} {}", i, j, k);
    }
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}