import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.io.PrintWriter
import java.lang.StringBuilder
import java.util.*

fun PrintWriter.solve(sc: FastScanner) {
    val h = sc.nextInt()
    val w = sc.nextInt()
    val sy = sc.nextInt() - 1
    val sx = sc.nextInt() - 1
    val gy = sc.nextInt() - 1
    val gx = sc.nextInt() - 1
    val map = Array(h) { Array(w) { '.' } }
    for (i in 0 until h) {
        val s = sc.nextLine()
        for (j in 0 until w) {
            map[i][j] = s[j]
        }
    }
    val visited = Array(h) { Array(w) { false } }
    val que: Queue<Triple<Int, Int, Int>> = ArrayDeque()
    que.add(Triple(sy, sx, 0))
    val d = arrayOf(1, 0, -1, 0, 1)
    while (que.count() > 0) {
        val (i, j, step) = que.poll()
        if (i == gy && j == gx) {
            println(step)
            return
        }
        for (k in 0 until 4) {
            val ny = i + d[k]
            val nx = j + d[k + 1]
            if (ny in 0 until h && nx in 0 until w && !visited[ny][nx] && map[ny][nx] == '.') {
                visited[ny][nx] = true
                que.add(Triple(ny, nx, step + 1))
            }
        }
    }
}

fun main(args: Array<String>) {
    val writer = PrintWriter(System.out, false)
    writer.solve(FastScanner(System.`in`))
    writer.flush()
}

class FastScanner(s: InputStream) {
    private var st = StringTokenizer("")
    private val br = BufferedReader(InputStreamReader(s))

    fun next(): String {
        while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())

        return st.nextToken()
    }

    fun nextInt() = next().toInt()
    fun nextLong() = next().toLong()
    fun nextLine() = br.readLine()
    fun nextDouble() = next().toDouble()
    fun ready() = br.ready()
}