const DXY: [(usize, usize); 4] = [(!0, 0), (0, 1), (1, 0), (0, !0)];
use std::collections::VecDeque;

use proconio::{input, marker::Usize1};
fn main() {
    input! {
        h: usize,
        w: usize,
        a: Usize1,
        b: Usize1,
        rc: [(Usize1, Usize1); 2],
        p: Usize1,
        q: Usize1,
    }
    let f = |i: usize, j: usize| rc[0].0 <= i && i <= rc[1].0 && rc[0].1 <= j && j <= rc[1].1;
    let mut dist: Vec<Vec<Vec<usize>>> = vec![vec![vec![1 << 60; 3]; w]; h];
    let mut que = VecDeque::new();
    que.push_back((a, b, 0, 0));
    dist[a][b][0] = 0;
    while let Some((i, j, mut x, d)) = que.pop_front() {
        if f(i, j) {
            x = x.max(1);
        }
        if x == 1 && (i, j) == (p, q) {
            x = x.max(2);
        }
        if dist[i][j][x] == 1 << 60 {
            dist[i][j][x] = d;
        }
        for (dx, dy) in DXY {
            let (px, py) = (i + dx, j + dy);
            if px < h && py < w {
                let mut x = x;
                if f(px, py) {
                    x = x.max(1);
                }
                if x == 1 && (px, py) == (p, q) {
                    x = x.max(2);
                }
                if dist[px][py][x] == 1 << 60 {
                    dist[px][py][x] = d + 1;
                    que.push_back((px, py, x, d + 1));
                }
            }
        }
    }
    println!("{}", dist[a][b][2]);
}