#include<cstdio>
FILE *in,*out;
int n,m,i,j,v[16][16],flag,poz1,poz2,s,min1,min2,smax=0;
bool lin[16],col[16];
void backtrack()
{
    int s=0,i,j,lsum;
    int z_flag;
    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
            s+=v[i][j];

    if(s>smax)smax=s;
    //linii
    for(i=0;i<n;i++)
    {
        if(!lin[i])
        {
             lsum=0;
            z_flag=0;
            for(j=0;j<m;j++)
            {
                v[i][j]*=-1;
                lsum+=v[i][j];
                if(v[i][j]==0)z_flag++;
            }
            if(z_flag!=m)
            {
                lin[i]=true;
                if(lsum>0)backtrack();
                lin[i]=false;
                for(j=0;j<m;j++)v[i][j]*=-1;
            }
        }
    }
    //coloane
    for(j=0;j<n;j++)
    {
        if(!col[i])
        {
            lsum=0;
            z_flag=0;
            for(i=0;i<n;i++)
            {
                v[i][j]*=-1;
                lsum+=v[i][j];
                if(v[i][j]==0)z_flag++;
            }
            if(z_flag!=n)
            {
                col[i]=true;
                if(lsum>0)backtrack();
                col[i]=false;
                for(i=0;i<n;i++)v[i][j]*=-1;
            }
        }
    }
}
int main()
{
    in=fopen("flip.in","r");
    fscanf(in,"%d %d",&n,&m);
    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
            fscanf(in,"%d",&v[i][j]);
    fclose(in);

    backtrack();

    out=fopen("flip.out","w");
    fprintf(out,"%d",smax);
    fclose(out);
}