#![allow(unused_imports, dead_code, unused_macros, unused_variables, non_snake_case, unused_parens)]
use std::cmp::*;
use std::mem::swap;
use std::collections::*;

const MOD:u64 = 1_000_000_007;
const INF:usize = 0x7fff_ffff_ffff_ffff;

macro_rules! min {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::min($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::min($a, min!($($rest),+))}};}
macro_rules! max {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::max($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::max($a, max!($($rest),+))}};}
macro_rules! chmin {($base:expr, $($cmps:expr),+ $(,)*) => {{let cmp_min = min!($($cmps),+);if $base > cmp_min {$base = cmp_min;true} else {false}}};}
macro_rules! chmax {($base:expr, $($cmps:expr),+ $(,)*) => {{let cmp_max = max!($($cmps),+);if $base < cmp_max {$base = cmp_max;true} else {false}}};}
macro_rules! mulvec {($x:expr; $s:expr) => {vec![$x; $s]};($x:expr; $s0:expr; $( $s:expr );+) => {mulvec![vec![$x; $s0]; $( $s );+ ]};}
macro_rules! outputln {($var:expr)=>{println!("{}",$var)};($var:expr,$($vars:expr),+)=>{print!("{} ",$var);outputln!($($vars),+);};}
macro_rules! debug {($($a:expr),* $(,)*) => {eprintln!(concat!($("| ",stringify!($a), "={:?} "),*, "|"),$(&$a),*);};}


fn solve() {
    input! {
        H: usize,
        W: usize,
        N: usize,
        ABCD:[(usize,usize,usize,usize);N],
    }
    let mut warp = HashMap::new();
	warp.insert((1,1), vec![]);
	warp.insert((H,W), vec![]);
	for &(a,b,c,d) in &ABCD {
		warp.entry((a,b)).or_insert(vec![]).push((c,d));
		warp.entry((c,d)).or_default();
	}
	let mut warp2 = vec![];
	let mut warp_pos = vec![];
	let mut start = 0;
	let mut goal = 0;
	let mut dict = HashMap::new();
	for (i, ((a,b), dst)) in warp.into_iter().enumerate() {
		dict.insert((a,b), i);
		warp2.push(dst);
		warp_pos.push((a,b));
		if (a,b) == (1,1) {
			start = i;
		}else if (a,b) == (H,W) {
			goal = i;
		}
	}
	let warp = warp2;
	let mut dist = vec![INF;warp.len()];
	let mut visit = vec![false;warp.len()];
	dist[start] = 0;
	// debug!(warp_pos);
	// debug!(dict);
	// debug!(start, goal);
	// debug!(warp);
	let mut que = BinaryHeap::new();
	que.push((Reverse(0), start));
	while let Some((Reverse(d), idx)) = que.pop() {
		if visit[idx]{continue}
		visit[idx] = true;
		// debug!(idx, d);
		// debug!(dist);
		// warp
		for &(i,j) in warp[idx].iter() {
			let idx2 = *dict.get(&(i,j)).unwrap();
			if dist[idx2] > d+1 {
				dist[idx2] = d+1;
				que.push((Reverse(d+1), idx2));
			}
		}
		let (i,j) = warp_pos[idx];
		for (idx2, &(i2,j2)) in warp_pos.iter().enumerate() {
			if visit[idx2] {continue}
			let d2 = d + i.abs_diff(i2) + j.abs_diff(j2);
			if d2 < dist[idx2] {
				dist[idx2] = d2;
				que.push((Reverse(d2), idx2));
			}
		}
	}
	outputln!(dist[goal]);
}

fn main() {
    std::thread::Builder::new()
        .stack_size(128 * 1024 * 1024)
        .spawn(|| solve()).unwrap()
        .join().unwrap();
}


mod _input {
    // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
    #[macro_export]
    macro_rules! input {
        (source = $s:expr, $($r:tt)*) => {
            let mut iter = $s.split_whitespace();
            let mut next = || { iter.next().unwrap() };
            input_inner!{next, $($r)*}
        };
        ($($r:tt)*) => {
            let stdin = std::io::stdin();
            let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
            let mut next = move || -> String{
                bytes
                    .by_ref()
                    .map(|r|r.unwrap() as char)
                    .skip_while(|c|c.is_whitespace())
                    .take_while(|c|!c.is_whitespace())
                    .collect()
            };
            input_inner!{next, $($r)*}
        };
    }
    #[macro_export]
    macro_rules! input_inner {
        ($next:expr) => {};
        ($next:expr, ) => {};

        ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
            let $var = read_value!($next, $t);
            input_inner!{$next $($r)*}
        };
    }
    #[macro_export]
    macro_rules! read_value {
        ($next:expr, ( $($t:tt),* )) => {
            ( $(read_value!($next, $t)),* )
        };

        ($next:expr, [ $t:tt ; $len:expr ]) => {
            (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
        };

        ($next:expr, chars) => {
            read_value!($next, String).chars().collect::<Vec<char>>()
        };

        ($next:expr, usize1) => {
            read_value!($next, usize) - 1
        };

        ($next:expr, $t:ty) => {
            $next().parse::<$t>().expect("Parse error")
        };
    }
}