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

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static long[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        var a = NArr(n);

        var dp1 = 0L;
        var dp2 = 0L;
        for (var i = 0; i < n; ++i)
        {
            var sum = 0L;
            for (var j = 0; j < m; ++j) sum += a[i][j];
            (dp1, dp2) = (Math.Max(dp1, dp2 + sum), Math.Max(dp2, dp1 - sum));
        }
        WriteLine(Math.Max(dp1, dp2));
    }
}