using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

using CHY72;

namespace CHY72{
    
    public class PointXY{
        public int X , Y;
        public int SQLength() { return X * X + Y * Y; }
        public bool Flag = false;
        public int ID = -1;
        public PointXY(int _X,int _Y,int _ID = 0) {
            X = _X; Y = _Y; ID = _ID;
        }
        public PointXY(PointXY P1, int _X = 0, int _Y = 0,int _ID = -1) {
            X = P1.X + _X; Y = P1.Y + _Y; ID = _ID;
        }
        public static bool operator ==(PointXY P1, PointXY P2) {
            return (P1.X== P2.X && P1.Y == P2.Y);
        }
        public static bool operator !=(PointXY P1, PointXY P2) {return !(P1 ==P2);}
        public override int GetHashCode() {return X.GetHashCode() ^ Y.GetHashCode();}
        public override bool Equals(object obj) {
            if (obj == null || this.GetType() != obj.GetType()) {return false;}
            return (this == (PointXY)obj);
        }
        public string CurrentInformation() {
            return "x:" + X + "  y:" + Y + "  ID:" + ID;
        } 

    }

    public class Lib72 {
        public static int NumFromChar(char CNUM) { return CNUM - 48; }
        public static char LoopChar52(char _C, int n) {
            //Char(C#) uses Uni-Code
            //33 !  "#$%&'(  41 )
            //42 * +,-.  47/
            //48 0  .... 57 9
            //58 :;<=>? 64 @
            //65 A .... 90 Z
            //91 [\]^_ 96`
            //97 a .... 122 z
            int i_C = (int)_C;
            if (i_C > 64 && i_C < 91) i_C -= 65;//0~25 AZ
            else if (i_C > 96 && i_C < 123) i_C -= 71;//26~51 az
            else return '0';
            int RESULT = Modulo ((i_C + n ) , 52);
            if(RESULT < 26) return (char)(RESULT+65);
            else return (char)(RESULT + 71);
        }
        public static int Modulo(int A, int B)  {
            // -6 % 5 == -1
            // -6 % 5 == 4
            int Result = A % B;
            if (Result >= 0) { return Result; }
            else return Result + B;
        }
        public static int intFromHourMinSec(int _h,int _m,int _s) {
            return _s + 60 * _m + 3600 * _h;
        }

        public static int[] KETAArray(int Num) {return KETAArray(Num.ToString()); }
        public static int[] KETAArray(string Num) {
            char[] cKETA = Num.ToCharArray();
            int[] iKETA = new int[cKETA.Length];
            for (int i = 0; i < iKETA.Length; i++) {
                iKETA[i] = NumFromChar(cKETA[i]);
            }
            return iKETA;
        }
        public static int KETA(int Num) { return Num.ToString().ToCharArray().Length; }
        public static int FromKETAArray(int[] _ketaarray) {
            int result = 0;
            int[] R_ketaarray = _ketaarray.Reverse().ToArray(); 
            for (int i = 0,j=1; i < R_ketaarray.Length; i++,j *=10) {
                result += j * R_ketaarray[i];
            }
            return result;
        }
        public static bool isPrime(int p) {
            if (p != 2 && p % 2 == 0) return false;
            if (p == 1) return false;
            int SQp = (int)(Math.Sqrt(p));
            for (int i = 3; i <= SQp; i++) {
                if (p % i == 0) return false;
            }
            return true;
        } 
    }
}    

public class Program {
    static bool ReadLine_1(ref int num1, bool Fin0 = true) {
        string str = Console.ReadLine();
        num1 = int.Parse(str);
        return (Fin0 && num1 == 0);
    }
    static int  ReadLine_1() {
        return  int.Parse(Console.ReadLine());
    }
    static bool ReadLine_2(ref int num1, ref int num2, char Spliter = ' ', bool Fin0 = true,int FinNum =0) {
        string str = Console.ReadLine();
        num1 = int.Parse(str.Split(Spliter)[0]);
        num2 = int.Parse(str.Split(Spliter)[1]);
        return (Fin0 && num1 == FinNum && num2 == FinNum);
    }
    static int[] ReadLine_Array(char Spliter = ' ') {
        return Console.ReadLine().Split(Spliter).Select(s => int.Parse(s)).ToArray();
    }

    /*
    static bool FileReadLine_1(ref int num1, bool Fin0 = true) {
        string str = cReader.ReadLine();
        num1 = int.Parse(str);
        return (Fin0 && num1 == 0);
    }
    static int FileReadLine_1() {
        return int.Parse(cReader.ReadLine());
    }
    static bool FileReadLine_2(ref int num1, ref int num2, char Spliter = ' ', bool Fin0 = true, int FinNum = 0) {
        string str = cReader.ReadLine();
        num1 = int.Parse(str.Split(Spliter)[0]);
        num2 = int.Parse(str.Split(Spliter)[1]);
        return (Fin0 && num1 == FinNum && num2 == FinNum);
    }
    static int[] FileReadLine_Array(char Spliter = ' ') {
        return cReader.ReadLine().Split(Spliter).Select(s => int.Parse(s)).ToArray();
    }
    */
    //static System.IO.StreamReader cReader ;

    const int DefaultMax = 72727272;



    static int w = 0, h = 0;
    static bool[][] DoorsX = new bool[1][];
    static bool[][] DoorsY = new bool[1][];

    static bool CanGo(int _Y, int _X, int GoY , int GoX ) {
        // GoX =[-1,0,1];GoY = [-1,0,1];
        if (_X == 0 && GoX < 0) return false;
        else if (_Y == 0 && GoY < 0) return false;
        else if (_X == w - 1 && GoX > 0) return false;
        else if (_Y == h - 1 && GoY > 0) return false;
        
        if ( GoY > 0)     return !DoorsY[_Y][_X];
        else if (GoX > 0) return !DoorsX[_Y][_X + 1];
        else if (GoY < 0) return !DoorsY[_Y - 1][_X];
        else if (GoX < 0) return !DoorsX[_Y][_X];
        else return false;
    }

    static void Main(string[] args) {
         //cReader = new System.IO.StreamReader(System.IO.Directory.GetCurrentDirectory() + "\\Read.txt", System.Text.Encoding.Unicode);
        

        
        while (true) {
            if (ReadLine_2(ref w, ref h)) return;
            DoorsX = new bool[h][];
            DoorsY = new bool[h - 1][];
            for (int i = 0; i < 2 * h - 1; i++) {
                string[] Reader =Console.ReadLine().Split(' ');
                if (i % 2 == 0) {
                    Reader[0] = "1";
                    DoorsX[i/2] = Reader.Select(s => ("1" == s)).ToArray();
                }else {
                    DoorsY[i/2] = Reader.Select(s => ("1" == s)).ToArray();
                }
            }
            
            Queue<PointXY> MyPos = new Queue<PointXY>() ;
            MyPos.Enqueue(new PointXY (0,0));
            int Searching = 0;
            bool [,] Searched = new bool[h,w];
            bool OK = false;
            Searched[0, 0] = true;
            while (MyPos .Count > 0) {
                var CurrentPos = MyPos.Dequeue();
                Searching = CurrentPos.ID;
                if (CurrentPos == new PointXY(w - 1, h - 1)) { OK = true; break; }
                Searching++;
                //Console.WriteLine(CurrentPos.CurrentInformation ());
                if (CanGo(CurrentPos.Y, CurrentPos.X, -1, 0) && !Searched[CurrentPos.Y - 1, CurrentPos.X]) { 
                    MyPos.Enqueue(new PointXY (CurrentPos,0,-1,Searching));
                    Searched[CurrentPos.Y -1, CurrentPos.X] = true;
                }
                if (CanGo(CurrentPos.Y, CurrentPos.X, 1, 0) && !Searched[CurrentPos.Y + 1, CurrentPos.X] ) { 
                    MyPos.Enqueue(new PointXY(CurrentPos, 0, 1, Searching));
                    Searched[CurrentPos.Y + 1 , CurrentPos.X] = true;
                }
                if (CanGo(CurrentPos.Y, CurrentPos.X, 0, -1) && !Searched[CurrentPos.Y , CurrentPos.X- 1] ) {
                    MyPos.Enqueue(new PointXY(CurrentPos, -1, 0, Searching));
                    Searched[CurrentPos.Y , CurrentPos.X - 1] = true;
                }
                if (CanGo(CurrentPos.Y, CurrentPos.X, 0, 1) && !Searched[CurrentPos.Y, CurrentPos.X + 1]) { 
                    MyPos.Enqueue(new PointXY(CurrentPos, 1, 0, Searching));
                    Searched[CurrentPos.Y , CurrentPos.X + 1] = true;
                }
  
            }
            if (!OK) Console.WriteLine(0);
            else Console.WriteLine(Searching + 1);

        }
        // cReader.Close();
    }
}

Measured memory_bytes: 6516