#include <stdio.h>
#include <string.h>
//fa combinatii de n luate cate k [0 la 16*2 -1]
int matrix[16][16];
int mat[16][16];
int n, m;
long maxim;

void calc_max()
{
    long s1=0;
    int i, j;

    for(i=0; i<n; i++)
        for(j=0; j<m; j++)
            s1+=mat[i][j];

    if(s1>maxim) maxim = s1;
}

void inmul_matrix(int v[], int k)
{
    int i, j;

    memcpy(mat, matrix, sizeof(mat));


    for (i=0; i<k; i++)
        if(v[i]<=n)
        {
            for (j=0; j<m; j++)
                mat[v[i]-1][j]*=-1;
        }
        else
        {
            for (j=0; j<n; j++)
                mat[j][v[i]-n-1]*=-1;
        }

    calc_max();

}

void combinari(int v[], int n, int k, int i, int r)
{
    int j;

    if(i==k)
    {
        inmul_matrix(v,k);
        return;
    }

    for(j=r; j<=n; j++)
    {
        v[i]=j;
        combinari(v, n, k, i+1, j+1);
    }

}


int main ()
{
    int i, j, k;
    int v[32];

    FILE *fi, *fo;
    fi=fopen("flip.in","r");
    fo=fopen("flip.out","w");

    fscanf(fi,"%d %d", &n, &m);

    for(i=0; i<n; i++)
        for(j=0; j<m; j++)
            fscanf(fi,"%d", &matrix[i][j]);

    for(i=1; i<n+m-2; i++)
        combinari(v, n+m, i, 0, 1);

    printf("%ld", maxim);
    fprintf(fo,"%ld", maxim);

    fclose(fi);
    fclose(fo);
}