using Lib;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using static Lib.OutputLib;
public class Solver
{
    const bool MultiTestCase = false;
    void Solve()
    {
        int h = ri, w = ri;
        CalcC(h, w);
        CalcT(h, w);
        CalcCT(h, w);
    }

    void CalcC(int h, int w)
    {
        int n = Math.Max(h, w);
        var f = new bool[n + 1, n + 1];
        for (int i = 0; i <= n; i++) f[i, 0] = true;
        for (int j = 0; j <= n; j++) f[0, j] = true;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
            {
                if (i >= 4 && i % 2 == 0 && j >= 3) f[i, j] |= true;
                if (i >= 3 && j >= 4 && j % 2 == 0) f[i, j] |= true;

                if (i > 1 && j > 2) f[i, j] |= f[i - 1, j - 2];
                if (i > 2 && j > 1) f[i, j] |= f[i - 2, j - 1];
            }
        // WriteMat(f);

        var a = new int[h, w];
        int cnt = 0;
        void calc(int h, int w, Action<int, int, int> set)
        {
            if (h == 0 || w == 0) return;
            if (!f[h, w])
            {
                cnt = -IINF;
                return;
            }
            if (h >= 4 && h % 2 == 0 && w >= 3)
            {
                while (h >= 6)
                {
                    for (int j = 0; j < w; j++)
                    {
                        set(0, j, cnt + 1);
                        set(1, j, cnt + 2);
                        set(2, j, cnt + 1);
                        set(3, j, cnt + 3);
                        set(4, j, cnt + 2);
                        set(5, j, cnt + 3);
                    }
                    set(1, 0, cnt + 1);
                    set(2, w - 1, cnt + 2);
                    set(3, w - 1, cnt + 2);
                    set(4, 0, cnt + 3);
                    cnt += 3;
                    h -= 6;
                }
                if (h >= 4)
                {
                    for (int j = 0; j < w; j++)
                    {
                        set(0, j, cnt + 1);
                        set(1, j, cnt + 2);
                        set(2, j, cnt + 1);
                        set(3, j, cnt + 2);
                    }
                    set(1, 0, cnt + 1);
                    set(2, w - 1, cnt + 2);
                    cnt += 2;
                    h -= 4;
                }
            }
            else if (h > 1 && w > 2 && f[h - 1, w - 2])
            {
                for (int i = 0; i < h; i++) set(i, 0, cnt + 1);
                for (int i = 0; i < h; i++) set(i, w - 1, cnt + 1);
                for (int j = 0; j < w; j++) set(0, j, cnt + 1);
                cnt += 1;
                calc(h - 1, w - 2, (i, j, v) => set(i + 1, j + 1, v));
            }
            else
            {
                calc(w, h, (i, j, v) => set(j, i, v));
            }
        }
        calc(h, w, (i, j, v) => a[i, j] = v);
        if (cnt < 0)
        {
            Write(-1);
        }
        else
        {
            Write(cnt);
            WriteMat(a);
        }
    }
    void CalcT(int h, int w)
    {
        int n = Math.Max(h, w);
        var f = new bool[n + 1, n + 1];
        for (int i = 0; i <= n; i++) f[i, 0] = true;
        for (int j = 0; j <= n; j++) f[0, j] = true;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
            {
                if (i >= 4 && j >= 4)
                {
                    f[i, j] |= f[i - 4, j];
                    f[i, j] |= f[i, j - 4];
                }
                if (i >= 5 && j >= 5) f[i, j] |= f[i - 5, j];
                if (i >= 5 && j >= 5) f[i, j] |= f[i, j - 5];
                if (i >= 6 && j >= 5) f[i, j] |= f[i - 6, j];
                if (i >= 5 && j >= 6) f[i, j] |= f[i, j - 6];

                if (i > 2 && j > 3) f[i, j] |= f[i - 2, j - 3];
                if (i > 3 && j > 2) f[i, j] |= f[i - 3, j - 2];
            }
        // WriteMat(f);

        var a = new int[h, w];
        int cnt = 0;
        void calc(int h, int w, Action<int, int, int> set)
        {
            if (h == 0 || w == 0) return;
            if (!f[h, w])
            {
                cnt = -IINF;
                return;
            }
            if (h > 3 && w > 2 && f[h - 3, w - 2])
            {
                for (int i = 0; i < h; i++) set(i, w - 1, cnt + 3);
                for (int j = 0; j < w; j++) set(2, j, cnt + 3);
                for (int j = 0; j < w; j++) set(0, j, cnt + 1);
                for (int i = 0; i < h; i++) set(i, 0, cnt + 2);
                for (int j = 0; j < w - 2; j++) set(1, j, cnt + 2);
                set(1, w - 2, cnt + 1);
                cnt += 3;
                calc(h - 3, w - 2, (i, j, v) => set(i + 3, j + 1, v));
            }
            else if (h >= 4 && w >= 4 && f[h - 4, w])
            {
                for (int i = 0; i < h - 1; i++) set(i, 0, cnt + 1);
                for (int j = 0; j < w - 2; j++) set(1, j, cnt + 1);
                for (int j = 1; j < w; j++) set(0, j, cnt + 2);
                for (int i = 0; i < h - 2; i++) set(i, w - 2, cnt + 2);
                for (int i = 1; i < h; i++) set(i, w - 1, cnt + 3);
                for (int j = 2; j < w; j++) set(h - 2, j, cnt + 3);
                for (int j = 0; j < w - 1; j++) set(h - 1, j, cnt + 4);
                for (int i = 2; i < h; i++) set(i, 1, cnt + 4);
                cnt += 4;
                calc(h - 4, w, (i, j, v) => set(i + 4, j, v));
            }
            else if (h >= 5 && w >= 5 && f[h - 5, w])
            {
                for (int i = 0; i < 5; i++)
                    for (int j = 0; j < w; j++)
                        set(i, j, cnt + 1 + i);
                set(1, 1, cnt + 1);
                set(2, w - 2, cnt + 2);
                set(1, 0, cnt + 3);
                set(3, 0, cnt + 3);
                set(2, w - 1, cnt + 4);
                set(4, w - 1, cnt + 4);
                set(3, 1, cnt + 5);
                cnt += 5;
                calc(h - 5, w, (i, j, v) => set(i + 5, j, v));
            }
            else if (h >= 6 && w >= 5 && f[h - 6, w])
            {
                for (int i = 0; i < 6; i++)
                    for (int j = 0; j < w; j++)
                        set(i, j, cnt + 1 + i);
                for (int i = 0; i < 5; i++) set(i, w - 1, cnt + 2);
                for (int i = 1; i < 6; i++) set(i, w - 1, cnt + 5);
                set(1, 1, cnt + 1);
                set(1, 2, cnt + 3);
                set(4, w - 3, cnt + 4);
                set(4, w - 2, cnt + 6);
                cnt += 6;
                calc(h - 6, w, (i, j, v) => set(i + 6, j, v));
            }
            else
            {
                calc(w, h, (i, j, v) => set(j, i, v));
            }
        }
        calc(h, w, (i, j, v) => a[i, j] = v);
        if (cnt < 0)
        {
            Write(-1);
        }
        else
        {
            Write(cnt);
            WriteMat(a);
        }
    }
    void CalcCT(int h, int w)
    {
        int n = Math.Max(h, w);
        var f = new bool[n + 1, n + 1];
        for (int i = 0; i <= n; i++) f[i, 0] = true;
        for (int j = 0; j <= n; j++) f[0, j] = true;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
            {
                if ((i == 3 || i == 4) && j >= 3) f[i, j] = true;
                if (i >= 3 && (j == 3 || j == 4)) f[i, j] = true;
                if (i > 1 && j > 2) f[i, j] |= f[i - 1, j - 2];
                if (i > 2 && j > 1) f[i, j] |= f[i - 2, j - 1];
            }
        // WriteMat(f);

        var a = new int[h, w];
        int cnt = 0;
        void calc(int h, int w, Action<int, int, int> set)
        {
            if (h == 0 || w == 0) return;
            if (!f[h, w])
            {
                cnt = -IINF;
                return;
            }
            if (h > w)
            {
                calc(w, h, (i, j, v) => set(j, i, v));
                return;
            }
            if (h == 3)
            {
                for (int j = 0; j < w; j++)
                {
                    set(0, j, cnt + 1);
                    set(1, j, cnt + 2);
                    set(2, j, cnt + 1);
                }
                set(0, w - 1, cnt + 2);
                set(1, 0, cnt + 1);
                set(2, w - 1, cnt + 2);
                cnt += 2;
            }
            else if (h == 4)
            {
                for (int j = 0; j < w; j++)
                {
                    set(0, j, cnt + 1);
                    set(1, j, cnt + 2);
                    set(2, j, cnt + 3);
                    set(3, j, cnt + 2);
                }
                set(1, w - 2, cnt + 1);
                set(1, w - 1, cnt + 3);
                set(2, 0, cnt + 2);
                set(3, w - 1, cnt + 3);
                cnt += 3;
            }
            else
            {
                for (int j = 0; j < w; j++) set(0, j, cnt + 1);
                for (int i = 0; i < h; i++) set(i, 0, cnt + 1);
                for (int j = 0; j < w; j++) set(h - 1, j, cnt + 1);
                cnt += 1;
                calc(h - 2, w - 1, (i, j, v) => set(i + 1, j + 1, v));
            }
        }
        calc(h, w, (i, j, v) => a[i, j] = v);
        if (cnt < 0)
        {
            Write(-1);
        }
        else
        {
            Write(cnt);
            WriteMat(a);
        }
    }

#pragma warning disable CS0162, CS8618
    public Solver() { if (!MultiTestCase) Solve(); else for (int t = ri; t > 0; t--) Solve(); }
#pragma warning restore CS0162, CS8618

    const int IINF = 1 << 30;
    const long INF = 1L << 60;
    int ri { [MethodImpl(256)] get => (int)sc.Integer(); }
    long rl { [MethodImpl(256)] get => sc.Integer(); }
    uint rui { [MethodImpl(256)] get => (uint)sc.UInteger(); }
    ulong rul { [MethodImpl(256)] get => sc.UInteger(); }
    double rd { [MethodImpl(256)] get => sc.Double(); }
    string rs { [MethodImpl(256)] get => sc.Scan(); }
    string rline { [MethodImpl(256)] get => sc.Line(); }
    public StreamScanner sc = new StreamScanner(Console.OpenStandardInput());
    void ReadArray(out int[] a, int n) { a = new int[n]; for (int i = 0; i < a.Length; i++) a[i] = ri; }
    void ReadArray(out long[] a, int n) { a = new long[n]; for (int i = 0; i < a.Length; i++) a[i] = rl; }
    void ReadArray<T>(out T[] a, int n, Func<T> read) { a = new T[n]; for (int i = 0; i < a.Length; i++) a[i] = read(); }
    void ReadArray<T>(out T[] a, int n, Func<int, T> read) { a = new T[n]; for (int i = 0; i < a.Length; i++) a[i] = read(i); }
}

static class Program
{
    static public void Main(string[] args)
    {
        SourceExpander.Expander.Expand();
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver();
        Console.Out.Flush();
    }
}
#region Expanded by https://github.com/kzrnm/SourceExpander
namespace Lib{public partial class StreamScanner{public StreamScanner(Stream stream){str=stream;}private readonly Stream str;private readonly byte[]buf=new byte[1024];private int len,ptr;public bool isEof=false;public bool IsEndOfStream{get{return isEof;}}[MethodImpl(256)]private byte Read(){if(isEof)throw new EndOfStreamException();if(ptr>=len){ptr=0;if((len=str.Read(buf,0,1024))<=0){isEof=true;return 0;}}return buf[ptr++];}[MethodImpl(256)]public char Char(){byte b;do b=Read();while(b<33||126<b);return(char)b;}[MethodImpl(256)]public string Line(){var sb=new StringBuilder();for(var b=Char();b!=10&&!isEof;b=(char)Read())sb.Append(b);return sb.ToString();}[MethodImpl(256)]public string Scan(){var sb=new StringBuilder();for(var b=Char();b>=33&&b<=126;b=(char)Read())sb.Append(b);return sb.ToString();}[MethodImpl(256)]public long Integer(){long ret=0;var ng=false;byte b;do b=Read();while(b!='-'&&(b<'0'||'9'<b));if(b=='-'){ng=true;b=Read();}for(;'0'<=b&&b<='9';b=Read())ret=ret*10+(b^'0');return ng?-ret:ret;}[MethodImpl(256)]public ulong UInteger(){ulong ret=0;byte b;do b=Read();while(b<'0'||'9'<b);for(;'0'<=b&&b<='9';b=Read())ret=ret*10+(ulong)(b^'0');return ret;}[MethodImpl(256)]public double Double()=>double.Parse(Scan());}}
namespace Lib{public static class OutputLib{[MethodImpl(256)]public static void WriteJoin<T>(string s,IEnumerable<T>t)=>Console.WriteLine(string.Join(s,t));[MethodImpl(256)]public static void WriteMat<T>(T[,]a,string sep=" "){int sz1=a.GetLength(0),sz2=a.GetLength(1);var b=new T[sz2];for(int i=0;i<sz1;i++){for(int j=0;j<sz2;j++)b[j]=a[i,j];WriteJoin(sep,b);}}[MethodImpl(256)]public static void WriteMat<T>(T[][]a,string sep=" "){foreach(var ar in a)WriteJoin(sep,ar);}[MethodImpl(256)]public static void WriteMat<T>(T[][]a,Func<T,string>map,string sep=" "){foreach(var ar in a)WriteJoin(sep,ar.Select(x=>map(x)));}[MethodImpl(256)]public static void Write(object t)=>Console.WriteLine(t.ToString());[MethodImpl(256)]public static void Write(params object[]arg)=>Console.WriteLine(string.Join(" ",arg.Select(x=>x.ToString())));[MethodImpl(256)]public static void Write(string str)=>Console.WriteLine(str);[MethodImpl(256)]public static void WriteFlush(object t){Console.WriteLine(t.ToString());Console.Out.Flush();}[MethodImpl(256)]public static void WriteError(object t)=>Console.Error.WriteLine(t.ToString());[MethodImpl(256)]public static void Flush()=>Console.Out.Flush();[MethodImpl(256)]public static void YN(bool t)=>Console.WriteLine(t?"YES":"NO");[MethodImpl(256)]public static void Yn(bool t)=>Console.WriteLine(t?"Yes":"No");[MethodImpl(256)]public static void yn(bool t)=>Console.WriteLine(t?"yes":"no");[MethodImpl(256)]public static void DeleteLine()=>Console.Write("\x1b[1A\x1b[2K");[MethodImpl(256)]public static void ProgressBar(long now,long total,int blocks=50){int x=(int)((2*now*blocks+1)/(2*total));Console.Write($"\x1b[G[\x1b[42m{string.Concat(Enumerable.Repeat("_",x))}\x1b[0m{string.Concat(Enumerable.Repeat("_",blocks-x))}] : {now} / {total}");}}}
namespace SourceExpander{public class Expander{[Conditional("EXP")]public static void Expand(string inputFilePath=null,string outputFilePath=null,bool ignoreAnyError=true){}public static string ExpandString(string inputFilePath=null,bool ignoreAnyError=true){return "";}}}
#endregion Expanded by https://github.com/kzrnm/SourceExpander