//use itertools::Itertools;
use std::cmp;
use std::collections::BTreeMap;
use std::collections::BTreeSet;
use std::collections::BinaryHeap;
use std::collections::HashMap;
use std::collections::HashSet;
use std::collections::VecDeque;
use std::io::Read;
use std::usize::MAX;

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_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_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, [ $t:tt ]) => {{let len = read_value!($next, usize);(0..len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()}};($next:expr, $t:ty) => {$next().parse::<$t>().expect("Parse error")};}

fn solve() {
    input! {
        h: usize,
        w:usize,
        c : (usize1,usize1),
        d: (usize1,usize1),
        maze: [chars;h]
    }

    let mut visited = vec![vec![false; w]; h];
    let mut dist = vec![vec![MAX; w]; h];

    let mut q = VecDeque::new();
    q.push_back((c.1, c.0, 0));
    while !q.is_empty() {
        let now = q.pop_back().unwrap();
        let now_x = now.0;
        let now_y = now.1;
        let now_dist = now.2;

        visited[now_y][now_x] = true;
        dist[now_y][now_x] = cmp::min(dist[now_y][now_x], now_dist);
        for i in 0..5 {
            for j in 0..5 {
                if now_x + i >= 2 && now_y + j >= 2 {
                    let new_x = now_x + i - 2;
                    let new_y = now_y + j - 2;

                    if new_x < w && new_y < h && maze[new_y][new_x] == '.' && !visited[new_y][new_x]
                    {
                        let x_abs = cmp::max(now_x, new_x) - cmp::min(now_x, new_x);
                        let y_abs = cmp::max(now_y, new_y) - cmp::min(now_y, new_y);

                        if (x_abs == 0 && y_abs == 1) || (x_abs == 1 && y_abs == 0) {
                            q.push_back((new_x, new_y, now_dist));
                        } else {
                            q.push_front((new_x, new_y, now_dist + 1));
                        }
                    }
                }
            }
        }
    }

    //println!("{:?}", dist);

    let start_dist = dist[c.0][c.1];
    let goal_dist = dist[d.0][d.1];

    if goal_dist == MAX {
        println!("{}", -1);
    } else {
        println!("{}", goal_dist);
    }
}

fn main() {
    let thd = std::thread::Builder::new().stack_size(104_857_600);
    thd.spawn(|| solve()).unwrap().join().unwrap();

    /*
    // 入力を一括で読み込む場合
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    let mut input = buf.split_whitespace();

    // inputに対しnext()で読み込んでいく
    let q: usize = input.next().unwrap().parse().unwrap();
    */
}

const LARGE_PRIME: u64 = 1_000_000_007;

// @〜でsnippet
struct UnionFind {
    parent: Vec<usize>,
    rank: Vec<usize>,
    size: Vec<usize>,
}

impl UnionFind {
    fn new(n: usize) -> UnionFind {
        UnionFind {
            parent: (0..n).collect(),
            rank: vec![0; n],
            size: vec![1; n],
        }
    }

    fn root(&mut self, x: usize) -> usize {
        let parent = self.parent[x];
        if parent != x {
            self.parent[x] = self.root(parent);
            self.rank[x] = 1;
        }
        return self.parent[x];
    }

    fn unite(&mut self, x: usize, y: usize) {
        if self.same(x, y) {
            return;
        }
        let x_root = self.root(x);
        let y_root = self.root(y);
        if self.rank[x_root] >= self.rank[y_root] {
            self.size[x_root] += self.size(y);
            self.rank[y_root] = 1;
            self.parent[y_root] = x_root;
        } else {
            let x_root = self.root(x);
            let y_root = self.root(y);
            self.size[y_root] += self.size(x);
            self.rank[x_root] = 1;
            self.parent[x_root] = y_root;
        }
    }

    fn size(&mut self, x: usize) -> usize {
        let x_root = self.root(x);
        return self.size[x_root];
    }

    fn same(&mut self, x: usize, y: usize) -> bool {
        self.root(x) == self.root(y)
    }
}


Measured memory_bytes: 19952