#include <iostream>
#include <stdio.h>
using namespace std;
int M,N,A[18][18],smax=0,v[33];
int suma ()
    { int i,j;
      int s=0;
      for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)s+=A[i][j]*v[j]*v[i+M];
      return s;

    }

void backt(int k)
    { int i;
      if(k==1){v[k]=1;backt(k+1);}
      else if(k==M+1){v[k]=1;
                      if(k==M+N){  int s=suma(); if(s<0)s*=(-1); if(s>smax)smax=s; }
                       else backt(k+1);}
      else for (i=-1;i<=1;i=i+2)
      {   v[k]=i;
          if(k==M+N){  int s=suma(); if(s<0)s*=(-1); if(s>smax)smax=s; }
          else backt(k+1);
      }


    }


int main()
{   FILE *f=fopen("flip.in","rt");
    FILE *g=fopen("flip.out","wt");
    int j;
    int i;
    fscanf(f,"%d %d",&N,&M);

    for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)
                {fscanf(f,"%d",&A[i][j]); smax+=A[i][j];}
    backt(1);
    fprintf(g,"%d\n",smax);

    fclose(f);
    fclose(g);
    return 0;
}