use std::cmp::Reverse;
use std::collections::{BinaryHeap, HashSet};

#[derive(Default)]
//NOTE
//declare variables to reduce the number of parameters for dp and dfs etc.
struct Solver {}

impl Solver {
    fn solve(&mut self) {
        let stdin = std::io::stdin();
        let mut scn = Scanner {
            stdin: stdin.lock(),
        };
        let h: usize = scn.read();
        let w: usize = scn.read();
        let ch: usize = scn.read::<usize>() - 1;
        let cw: usize = scn.read::<usize>() - 1;
        let dh: usize = scn.read::<usize>() - 1;
        let dw: usize = scn.read::<usize>() - 1;
        let s: Vec<_> = (0..h).map(|_| scn.chars()).collect();
        let mut que = BinaryHeap::new();
        let mut visited = HashSet::new();
        que.push(Reverse((0, ch, cw)));

        while let Some(p) = que.pop() {
            let p = p.0;
            let (cnt, y, x) = p;
            if y == dh && x == dw {
                println!("{}", cnt);
                return;
            }
            if visited.contains(&(y, x)) {
                continue;
            }
            visited.insert((y, x));

            //next no magic
            for dir in 0..4 {
                if let Some(nxt) = utils::try_adj(y, x, dir, h, w) {
                    let (ny, nx) = nxt;
                    if visited.contains(&(ny, nx)) {
                        continue;
                    }
                    if s[ny][nx] == '#' {
                        continue;
                    }
                    que.push(Reverse((cnt, ny, nx)));
                }
            }
            //next magic
            for i in -2..=2 {
                for j in -2..=2 {
                    let ny = i + y as i32;
                    let nx = j + x as i32;
                    if ny < 0 || ny >= h as i32 || nx < 0 || nx >= w as i32 {
                        continue;
                    }
                    let ny = ny as usize;
                    let nx = nx as usize;
                    if visited.contains(&(ny, nx)) {
                        continue;
                    }
                    if s[ny][nx] == '#' {
                        continue;
                    }
                    que.push(Reverse((cnt + 1, ny, nx)));
                }
            }
        }
        println!("{}", -1);
    }
}

fn main() {
    std::thread::Builder::new()
        .stack_size(64 * 1024 * 1024) // 64MB
        .spawn(|| {
            let mut solver = Solver::default();
            solver.solve()
        })
        .unwrap()
        .join()
        .unwrap();
}
pub mod utils {
    const DYX: [(isize, isize); 8] = [
        (0, 1),   //right
        (1, 0),   //down
        (0, -1),  //left
        (-1, 0),  //top
        (1, 1),   //down right
        (-1, 1),  //top right
        (1, -1),  //down left
        (-1, -1), //top left
    ];

    pub fn try_adj(y: usize, x: usize, dir: usize, h: usize, w: usize) -> Option<(usize, usize)> {
        let ny = y as isize + DYX[dir].0;
        let nx = x as isize + DYX[dir].1;
        if ny >= 0 && nx >= 0 {
            let ny = ny as usize;
            let nx = nx as usize;
            if ny < h && nx < w {
                Some((ny, nx))
            } else {
                None
            }
        } else {
            None
        }
    }
}

//snippet from kenkoooo
pub struct Scanner<R> {
    stdin: R,
}

impl<R: std::io::Read> Scanner<R> {
    pub fn read<T: std::str::FromStr>(&mut self) -> T {
        use std::io::Read;
        let buf = self
            .stdin
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b' ' || b == b'\n' || b == b'\r')
            .take_while(|&b| b != b' ' && b != b'\n' && b != b'\r')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn read_line(&mut self) -> String {
        use std::io::Read;
        let buf = self
            .stdin
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b'\n' || b == b'\r')
            .take_while(|&b| b != b'\n' && b != b'\r')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn vec<T: std::str::FromStr>(&mut self, n: usize) -> Vec<T> {
        (0..n).map(|_| self.read()).collect()
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.read::<String>().chars().collect()
    }
}


Measured memory_bytes: 19288