using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (h, w) = (c[0], c[1]);
        var map = NArr(h);
        var ri = new int[h];
        var dn = new int[w];
        var sl = new int[h + w - 1];
        var bs = new int[h + w - 1];
        var rset = new HashSet<int>[h];
        for (var i = 0; i < rset.Length; ++i) rset[i] = new HashSet<int>();
        var dset = new HashSet<int>[w];
        for (var i = 0; i < dset.Length; ++i) dset[i] = new HashSet<int>();
        var sset = new HashSet<int>[h + w - 1];
        for (var i = 0; i < sset.Length; ++i) sset[i] = new HashSet<int>();
        var bset = new HashSet<int>[h + w - 1];
        for (var i = 0; i < bset.Length; ++i) bset[i] = new HashSet<int>();
        for (var i = 0; i < h; ++i) for (var j = 0; j < w; ++j)
        {
            ri[i] += map[i][j];
            rset[i].Add(i * w + j);
            dn[j] += map[i][j];
            dset[j].Add(i * w + j);
            sl[i + j] += map[i][j];
            sset[i + j].Add(i * w + j);
            bs[i - j  + w - 1] += map[i][j];
            bset[i - j + w - 1].Add(i * w + j);
        }
        var ans = 0;
        for (var i = 0; i < h; ++i) for (var j = i + 1; j < h; ++j) ans = Math.Max(ans, ri[i] + ri[j]);
        for (var i = 0; i < w; ++i) for (var j = i + 1; j < w; ++j) ans = Math.Max(ans, dn[i] + dn[j]);
        for (var i = 0; i < sl.Length; ++i) for (var j = i + 1; j < sl.Length; ++j) ans = Math.Max(ans, sl[i] + sl[j]);
        for (var i = 0; i < bs.Length; ++i) for (var j = i + 1; j < bs.Length; ++j) ans = Math.Max(ans, bs[i] + bs[j]);
        for (var i = 0; i < h; ++i)
        {
            for (var j = 0; j < w; ++j) ans = Math.Max(ans, ri[i] + dn[j] - map[i][j]);
            for (var j = 0; j < sl.Length; ++j)
            {
                var cx = -1;
                var cy = -1;
                foreach (var p in sset[j]) if(rset[i].Contains(p))
                {
                    (cx, cy) = (p / w, p % w);
                    break;
                }
                ans = Math.Max(ans, ri[i] + sl[j] - (cx >= 0 ? map[cx][cy] : 0));
            }
            for (var j = 0; j < bs.Length; ++j)
            {
                var cx = -1;
                var cy = -1;
                foreach (var p in bset[j]) if (rset[i].Contains(p))
                {
                    (cx, cy) = (p / w, p % w);
                    break;
                }
                ans = Math.Max(ans, ri[i] + bs[j] - (cx >= 0 ? map[cx][cy] : 0));
            }
        }
        for (var i = 0; i < w; ++i)
        {
            for (var j = 0; j < sl.Length; ++j)
            {
                var cx = -1;
                var cy = -1;
                foreach (var p in sset[j]) if (dset[i].Contains(p))
                {
                    (cx, cy) = (p / w, p % w);
                    break;
                }
                ans = Math.Max(ans, dn[i] + sl[j] - (cx >= 0 ? map[cx][cy] : 0));
            }
            for (var j = 0; j < bs.Length; ++j)
            {
                var cx = -1;
                var cy = -1;
                foreach (var p in bset[j]) if (dset[i].Contains(p))
                {
                    (cx, cy) = (p / w, p % w);
                    break;
                }
                ans = Math.Max(ans, dn[i] + bs[j] - (cx >= 0 ? map[cx][cy] : 0));
            }
        }
        for (var i = 0; i < sl.Length; ++i) for (var j = 0; j < bs.Length; ++j)
        {
            var cx = -1;
            var cy = -1;
            foreach (var p in bset[j]) if (sset[i].Contains(p))
            {
                (cx, cy) = (p / w, p % w);
                break;
            }
            ans = Math.Max(ans, sl[i] + bs[j] - (cx >= 0 ? map[cx][cy] : 0));
        }
        WriteLine(ans);
    }
}