#include<fstream.h>
char l[17],c[17];
long long a[17][17],i,j,n,m,s,k=1,k2,t2,max=0,t=1,q;
int main()
{ifstream f("flip.in");ofstream h("flip.out");f>>n>>m;
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
f>>a[i][j];

memset(l,0,sizeof(l));

while(k<=n)

{memset(c,0,sizeof(c));k2=1;


while(k2<=m)
{s=0;

for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
if(l[i]==1 && c[j]==1) s=s+a[i][j];
else if(c[j]==1 || l[i]==1) s=s+(-1*a[i][j]);
      else s=s+a[i][j];
if(s>max) max=s;
for(q=1,t=1;t>0;q++)
if(c[q]==0) {c[q]=1;t=0;k2=q;}
else {c[q]=0;t=1;}
}
for(q=1,t=1;t>0;q++)
if(l[q]==0) {l[q]=1;t=0;k=q;}
 else {l[q]=0;t=1;}}





h<<max;
return 0;}