using System;
using System.Collections.Generic;
using System.Linq;

public class Program
{
    public static int width;
    public static int length;
    public static Queue<Node> queue = new Queue<Node>();

    public static void Main(string[] args)
    {
        string line = Console.ReadLine();
        width = (int)Char.GetNumericValue(line[0]);
        length = (int)Char.GetNumericValue(line[2]);
        var grid = new Node[width, length];
        int atLine = 0;


        while ((line = Console.ReadLine()) != null)
        {
            var currentLine = line.ToCharArray().Select(x => {
                var num = (int)Char.GetNumericValue(x);
                if (num < 0 || num > 9) return 0;
                else return num;
            }).ToArray();
                for (int j = 0; j < length; j++)
                {
                    if (j >= currentLine.Length) grid[atLine, j] = new Node(0);
                    else grid[atLine, j] = new Node(currentLine[j]);
                }
            if (++atLine == width) break;
        }

        initGraph(grid);
        /*Console.WriteLine();
        PrintArray(grid);
        Console.WriteLine();
        PrintNodes(grid);*/

        BFS(grid[0, 0], grid[width - 1, length - 1]);
        //PrintVisited(grid);
    }

    private static void BFS(Node start, Node goal)
    {
        start.level = 0;
        start.visited = true;
        queue.Enqueue(start);
        while (queue.Count > 0)
        {
            Node node = queue.Dequeue();
            foreach (var n in node.nodes)
            {
                if (!n.visited)
                {
                    n.level = node.level + 1;
                    n.visited = true;
                    queue.Enqueue(n);
                    if (n == goal)
                    {
                        Console.WriteLine(n.level);
                        return;
                    }
                }
            }
        }
        Console.WriteLine(-1);
    }

    public static void initGraph(Node[,] nodes)
    {
        for (int i = 0; i < nodes.GetLength(0); i++)
        {
            for (int j = 0; j < nodes.GetLength(1); j++)
            {
                var currentNode = nodes[i, j];
                int mvAmount = currentNode.mvAmount;
                if (mvAmount == 0) continue;
                int right = j + mvAmount;
                int left = j - mvAmount;
                int down = i + mvAmount;
                int up = i - mvAmount;
                if (right < length) currentNode.AddNode(nodes[i, right]);
                if (left >= 0) currentNode.AddNode(nodes[i, left]);
                if (down < width) currentNode.AddNode(nodes[down, j]);
                if (up >= 0) currentNode.AddNode(nodes[up, j]);
            }
        }
    }

    public static void PrintArray(Node[,] array)
    {
        int i = 0;
        foreach (var item in array)
        {
            Console.Write(item.mvAmount + " ");
            if (++i % length == 0) Console.WriteLine();
        }
    }

    public static void PrintNodes(Node[,] nodes)
    {
        int i = 0;

        foreach (var n in nodes)
        {
            Console.Write(n.nodes.Count + " ");
            if (++i % length == 0) Console.WriteLine();
        }
    }

    public static void PrintVisited(Node[,] nodes)
    {
        int i = 0;

        foreach (var n in nodes)
        {
            Console.Write(n.visited + " ");
            if (++i % length == 0) Console.WriteLine();
        }
    }

    public class Node
    {
        public int level { get; set; }
        public bool visited { get; set; }
        public int mvAmount { get; set; }
        public List<Node> nodes = new List<Node>();
        public Node(int mvAmount)
        {
            this.mvAmount = mvAmount;
            visited = false;
        }

        public void AddNode(Node n)
        {
            nodes.Add(n);
        }
    }
}