#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

fn main() {
    input! {
       H:usize,
       W:usize,
       Ch:Usize1,
       Cw:Usize1,
       Dh:Usize1,
       Dw:Usize1,
       map:[Chars;H],
    }

    let mut ans: usize = 0;
    let mut used = vec![vec![false; W]; H];
    let mut map2 = vec![vec![0; W]; H];
    let mut g = 1_usize;
    let mut kouho = VecDeque::new();
    for i in 0..H {
        for j in 0..W {
            if used[i][j] {
                continue;
            } else if map[i][j] == '#' {
                continue;
            }
            kouho.push_back((i, j));
            map2[i][j] = g;
            let dir: Vec<i32> = vec![-1, 0, 1, 0, -1, 1, 1, -1, -1];

            while !kouho.is_empty() {
                let (a2, b2) = kouho.pop_front().unwrap();

                for k in 0..4 {
                    let a = a2 as i32 + dir[k];
                    let b = b2 as i32 + dir[k + 1];
                    if a >= 0 && b >= 0 && a < H as i32 && b < W as i32 {
                        if map[a as usize][b as usize] != '#' {
                            if used[a as usize][b as usize] {
                                continue;
                            }
                            map2[a as usize][b as usize] = g;
                            used[a as usize][b as usize] = true;
                            kouho.push_back((a as usize, b as usize));
                        }
                    }
                }
            }
            g += 1;
        }
    }
    mydbg!(map2);

    let mut map3 = vec![vec![]; g];
    let mut used = vec![vec![false; W]; H];
    let mut kouho = VecDeque::new();
    let mut cache = HashSet::new();
    for i in 0..H {
        for j in 0..W {
            if used[i][j] {
                continue;
            } else if map[i][j] == '#' {
                continue;
            }
            kouho.push_back((i, j));
            let dir: Vec<i32> = vec![-1, 0, 1, 0, -1, 1, 1, -1, -1];

            while !kouho.is_empty() {
                let (a2, b2) = kouho.pop_front().unwrap();
                let mut flag = false;
                for k in 0..4 {
                    let a = a2 as i32 + dir[k];
                    let b = b2 as i32 + dir[k + 1];
                    if a >= 0 && b >= 0 && a < H as i32 && b < W as i32 {
                        if map[a as usize][b as usize] != '#' {
                            if used[a as usize][b as usize] {
                                continue;
                            }
                            used[a as usize][b as usize] = true;
                            kouho.push_back((a as usize, b as usize));
                        } else {
                            flag = true;
                        }
                    }
                }
                if flag {
                    let dir = [
                        (0, 1),
                        (1, 0),
                        (1, 1),
                        (0, -1),
                        (-1, 0),
                        (-1, -1),
                        (1, -1),
                        (-1, 1),
                        (2, 0),
                        (2, 1),
                        (2, 2),
                        (1, 2),
                        (0, 2),
                        (-1, 2),
                        (-2, 2),
                        (-2, 1),
                        (-2, 0),
                        (-2, -1),
                        (-2, -2),
                        (-1, 2),
                        (0, -2),
                        (1, -2),
                        (2, -2),
                        (2, -1),
                    ];
                    for k in 0..dir.len() {
                        let a = a2 as i32 + dir[k].0;
                        let b = b2 as i32 + dir[k].1;
                        if a >= 0 && b >= 0 && a < H as i32 && b < W as i32 {
                            let a = a as usize;
                            let b = b as usize;
                            let c = map2[a2][b2];
                            let d = map2[a][b];
                            if c == d {
                                continue;
                            } else if map[a][b] == '#' {
                                continue;
                            }
                            if !cache.contains(&(min(c, d), max(c, d))) {
                                map3[c].push(d);
                                map3[d].push(c);
                                cache.insert((min(c, d), max(c, d)));
                            }
                        }
                    }
                }
            }
        }
    }

    mydbg!(map2[Ch][Cw], map2[Dh][Dw]);
    if map2[Ch][Cw] == map2[Dh][Dw] {
        if map2[Ch][Cw] == 0 || map2[Dh][Dw] == 0 {
            panic!("hoge");
        }
        echo!(0);
    } else {
        let mut ans = -1;
        let mut kouho = VecDeque::new();
        kouho.push_back((map2[Ch][Cw], 0));
        let mut used = vec![-1; g];
        used[map2[Ch][Cw]] = 0;

        while !kouho.is_empty() {
            let (p, depth) = kouho.pop_front().unwrap();

            for i in 0..map3[p].len() {
                let next = map3[p][i];
                if used[next] != -1 {
                    continue;
                }
                used[next] = depth + 1;
                kouho.push_back((next, depth + 1));
            }
        }
        echo!(used[map2[Dh][Dw]]);
    }
    mydbg!(map3);
}


Measured memory_bytes: 30804