#include <stdlib.h>
#include <stdio.h>
#include <string.h>
//#include "Util.h"


int Sum(int **m, int row, int col)
{
    // Calculate the sum
    int s = 0;
    for(int i = 0; i < row; i++)
    {
        for(int j = 0; j < col; j++)
        {
            s += m[i][j];
        }
    }
    return s;
}

int sol[] = {1, -1};

static int f = 0;
void rec(int **m, int row, int col, int ii, int jj, int *s)
{
    int ss = 0;
    if(ii > row - 1 || jj > col -1) return;
    ss = Sum(m, row, col);
    if( ss > *s ) 
        *s = ss;

    //printf("%d\n",f++);
    //Util::Print(m, row, col);
    
    for(int k = 0; k < 2; k++)
    {
        for(int i = 0; i < row; i++)
        {
            m[i][jj] *= sol[k];
        }
        rec(m, row, col, ii, jj+1, s);

        for(int j = 0; j < col; j++)
        {
            m[ii][j] *= sol[k];
        }
        rec(m, row, col, ii+1, jj, s);
    }
}

int main()
{
    FILE * m_pFileIn, * m_pFileOut;
    m_pFileIn = fopen ("flip.in","r");
    int row = 0, col = 0;
    // read row and col 
    fscanf(m_pFileIn, "%d %d", &row, &col);
    // read the elements
    int **m = (int**) malloc(sizeof(int*) * row);
    for( int i = 0; i < row; i++ )
    {
        m[i] = (int*)malloc(sizeof(int*)*col);
        for(int j = 0; j < col; j++)
        {
            fscanf(m_pFileIn, "%d", &m[i][j]);
        }
    }
     
    int s = 0 ;  
    
    rec(m, row, col, 0, 0, &s);
    //printf("%d",s);
    
    m_pFileOut = fopen ("flip.out","w");
    fprintf(m_pFileOut, "%d", s);
    
    return 0 ;
}