#include<stdio.h>
#include<conio.h>

int main()
{
    int a[16][16];
    int i,j,n,m,s,sum;
    freopen("flip.in","r",stdin);
    freopen("flip.out","w",stdout);
    scanf("%d%d",&n,&m);
    s = 0;
    for(i=0;i<n;++i)
    for(j=0;j<m;++j)
    {
       scanf("%d",&a[i][j]);
       s += a[i][j];
    }
  
    int nn = 1<<n;
    int mm = 1<<m;
    int ii,jj;
    
    for(ii=0;ii<nn;++ii)
    for(jj=0;jj<mm;++jj)
    {
        sum = 0;
        for(i=0;i<n;++i)
        for(j=0;j<m;++j)
        if( (((1<<i)&ii)>>i) == (((1<<j)&jj)>>j) )
            sum += a[i][j];
        else
            sum -= a[i][j];
        if(sum > s)
            s = sum;
    }
    
    printf("%d",s);     
    return 0;    
}