#include<stdio.h>
int x,k,s,max,l,n,m,i,j,k2,l2;
int a[17][17];
int b[17][17];
int c[17][17];
int v[20],t[33000][20];


int main(){
  FILE *f=fopen("flip.in","r");

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

 for(i=1;i<=n;i++){
    for(j=1;j<=m;j++){
    fscanf(f,"%d",&a[i][j]);
    }
 }

 max=0;

fclose(f);


  for(i=0;i<=(1<<n)-1;i++){
  x++;
    for(j=n-1;j>=0;j--){
    t[x][j+1]=(i>>j)&1;
    }

  }


 for(k=0;k<=(1<<m)-1;k++){

   for(l=m-1;l>=0;l--){
   v[l+1]=(k>>l)&1;
   }


    for(k2=1;k2<=x;k2++){

	for(i=1;i<=n;i++){
	 if(t[k2][i]==1){
	   for(j=1;j<=m;j++)b[i][j]=(-1)*a[i][j];
	 }

	 else for(j=1;j<=m;j++)b[i][j]=a[i][j];

	}


     for(j=1;j<=m;j++){
       if(v[j]==1)
	 for(i=1;i<=n;i++) c[i][j]=(-1)*b[i][j];

       else  for(i=1;i<=n;i++) c[i][j]=b[i][j];

     }

     s=0;
     for(i=1;i<=n;i++){
	for(j=1;j<=m;j++){
	s=s+c[i][j];
	}
     }

    if(s>max){max=s;}

   }

 }

 FILE *g=fopen("flip.out","w");
 fprintf(g,"%d\n",max);
 fclose(g);

return 0;
}