import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int h = sc.nextInt();
        int w = sc.nextInt();
        int sr = sc.nextInt() - 1;
        int sx = sc.nextInt() - 1;
        int gr = sc.nextInt() - 1;
        int gc = sc.nextInt() - 1;
        char[][] field = new char[h][];
        for (int i = 0; i < h; i++) {
            field[i] = sc.next().toCharArray();
        }
        int[][][] costs = new int[h][w][6];
        for (int[][] arr : costs) {
            for (int[] arr1 : arr) {
                Arrays.fill(arr1, Integer.MAX_VALUE);
            }
        }
        PriorityQueue<Path> queue = new PriorityQueue<>();
        queue.add(new Path(sr, sx, 0, 0));
        while (queue.size() > 0) {
            Path p = queue.poll();
            if (field[p.r][p.c] == '#') {
                continue;
            }
            if (costs[p.r][p.c][p.idx] <= p.value) {
                continue;
            }
            costs[p.r][p.c][p.idx] = p.value;
            if (p.r > 0) {
                int nextIdx = p.idx;
                if (p.idx <= 2) {
                    nextIdx++;
                } else if(p.idx == 3) {
                    nextIdx = 0;
                }
                queue.add(new Path(p.r - 1, p.c, p.value + 1, nextIdx));
            }
            if (p.r < h - 1) {
                int nextIdx = p.idx;
                if (p.idx == 0) {
                    nextIdx = 3;
                } else if (p.idx <= 3) {
                    nextIdx--;
                }
                queue.add(new Path(p.r + 1, p.c, p.value + 1, nextIdx));
            }
            if (p.c > 0) {
                int nextIdx;
                if (p.idx == 0) {
                    nextIdx = 4;
                } else if (p.idx == 4) {
                    nextIdx = 2;
                } else if (p.idx == 2) {
                    nextIdx = 5;
                } else if (p.idx == 5) {
                    nextIdx = 0;
                } else {
                    nextIdx = p.idx;
                }
                queue.add(new Path(p.r, p.c - 1, p.value + 1, nextIdx));
            }
            if (p.c < w - 1) {
                int nextIdx;
                if (p.idx == 0) {
                    nextIdx = 5;
                } else if (p.idx == 5) {
                    nextIdx = 2;
                } else if (p.idx == 2) {
                    nextIdx = 4;
                } else if (p.idx == 4) {
                    nextIdx = 0;
                } else {
                    nextIdx = p.idx;
                }
                queue.add(new Path(p.r, p.c + 1, p.value + 1, nextIdx));
            }
        }
        if (costs[gr][gc][0] == Integer.MAX_VALUE) {
            System.out.println(-1);
        } else {
            System.out.println(costs[gr][gc][0]);
        }
    }
    
    static class Path implements Comparable<Path> {
        int r;
        int c;
        int value;
        int idx;
        
        public Path(int r, int c, int value, int idx) {
            this.r = r;
            this.c = c;
            this.value = value;
            this.idx = idx;
        }
        
        public int compareTo(Path another) {
            return value - another.value;
        }
    }
}


class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}