using System;
using System.IO;
using System.Text;
using System.Linq;
using System.Diagnostics;
using System.Collections.Generic;
using Enu = System.Linq.Enumerable;

class Program
{
    static readonly int[] dr = { 0, 0, -1, 1 };
    static readonly int[] dc = { -1, 1, 0, 0 };
    static readonly int INF = (int)1e9;
    int H, W;

    void Solve()
    {
        W = reader.Int();
        H = reader.Int();
        var grid = reader.IntGrid(H);
        var que = new Queue<State>();
        var minCost = new int[H, W, 10];
        Fill(minCost, INF);
        minCost[0, 0, 0] = 0;
        que.Enqueue(new State(-1, grid[0][0], 0, 0, 0));

        while (que.Count > 0)
        {
            var s = que.Dequeue();
            if (s.r == H - 1 && s.c == W - 1)
            {
                Console.WriteLine(s.steps);
                return;
            }
            for (int d = 0; d < dr.Length; d++)
            {
                int nr = s.r + dr[d], nc = s.c + dc[d];
                if (OK(s, nr, nc, grid))
                {
                    if (s.steps + 1 < minCost[nr, nc, s.curr])
                    {
                        minCost[nr, nc, s.curr] = s.steps + 1;
                        que.Enqueue(new State(s.curr, grid[nr][nc], nr, nc, s.steps + 1));
                    }
                }
            }
        }

        Console.WriteLine(-1);
    }

    private bool OK(State s, int nr, int nc, int[][] grid)
    {
        if (!IsInside(nr, nc)) return false;
        int next = grid[nr][nc];
        if (s.prev == next || s.curr == next) return false;
        if (s.prev < 0) return true;
        int mid = new[] { s.prev, s.curr, next }.OrderBy(e => e).ElementAt(1);
        return mid == s.prev || mid == next;
    }
    bool IsInside(int r, int c) { return r >= 0 && r < H && c >= 0 && c < W; }

    struct State
    {
        public short prev, curr, r, c;
        public int steps;
        public State(int p2, int p1, int r, int c, int step)
        {
            prev = (short)p2; curr = (short)p1; this.r = (short)r; this.c = (short)c; steps = step;
        }
    }

    void Fill<T>(T[, ,] a, T val)
    {
        for (int i = 0; i < a.GetLength(0); i++)
            for (int j = 0; j < a.GetLength(1); j++)
                for (int k = 0; k < a.GetLength(2); k++)
                    a[i, j, k] = val;
    }




    static void Main() { new Program().Solve(); }
    Reader reader = new Reader(Console.In);
    class Reader
    {
        private readonly TextReader reader;
        private readonly char[] separator = { ' ' };
        private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
        private string[] A = new string[0];
        private int i;

        public Reader(TextReader r) { reader = r; }
        public bool HasNext() { return Enqueue(); }
        public string String() { return Dequeue(); }
        public int Int() { return int.Parse(Dequeue()); }
        public long Long() { return long.Parse(Dequeue()); }
        public double Double() { return double.Parse(Dequeue()); }
        public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
        public int[] IntArray(int N) { return Enumerable.Range(0, N).Select(i => Int()).ToArray(); }
        public int[][] IntGrid(int H) { return Enumerable.Range(0, H).Select(i => IntLine()).ToArray(); }
        public string[] StringArray(int N) { return Enumerable.Range(0, N).Select(i => Line()).ToArray(); }
        public string Line() { return reader.ReadLine().Trim(); }
        private string[] Split(string s) { return s.Split(separator, removeOp); }
        private bool Enqueue()
        {
            if (i < A.Length) return true;
            string line = reader.ReadLine();
            if (line == null) return false;
            if (line == "") return Enqueue();
            A = Split(line);
            i = 0;
            return true;
        }
        private string Dequeue() { Enqueue(); return A[i++]; }
    }
}