#include<stdarg.h>
#include<stdio.h>
#include<limits.h>
#define testpoint(text) {fputs(text,stderr);va_end(ap);return 0;}
#define instd() (ifl__=stdin)
#define outstd() (ofl__=stdout)
#define inopen(filename) (ifl__=fopen((filename),"r"))
#define outopen(filename) (ofl__=fopen((filename),"w"))
#define inclose() fclose(ifl__)
#define outclose() fclose(ofl__)
#define bothclose() (inclose(),outclose())
#define bothopen(filename) (inopen(filename ".in"),outopen(filename ".out"))
FILE*ifl__;FILE*ofl__;filread(char*ft,...){va_list ap;va_start
(ap,ft);void*p;char*ift=ft;int i;for(;*ft;ft++)switch(*ft)
{case' ':continue;case'S':p=va_arg(ap,char*);fgets
((char*)p,INT_MAX,ifl__);break;case'l':p=va_arg(ap,long 
int*);fscanf(ifl__,"%ld\n",(long int*)p);break;case'L':p=va_arg
(ap,long long int*);fscanf(ifl__,"%lld\n",(long long 
int*)p);break;case'd':p=va_arg(ap,int*);fscanf(ifl__,"%d\n",
(int*)p);break;case'N':i=*va_arg(ap,int*);if(*++ft=='D')for
(p=va_arg(ap,int*);i--;p=(int*)p+1)fscanf(ifl__,i?"%d ":"%d\n",
(int*)p);else if(*ft=='l')for(p=va_arg(ap,long int*);i--;p=
(long int*)p+1)fscanf(ifl__,i?"%ld ":"%ld\n",(long int*)p);else 
if(*ft=='L')for(p=va_arg(ap,long long int*);i--;p=(long long 
int*)p+1)fscanf(ifl__,i?"%lld ":"%lld\n",(long long 
int*)p);else goto fterror;break;default:goto 
fterror;fterror:fprintf(stderr,
"Error in format specifier at position %d\n",ft-ift);va_end
(ap);return 1;}va_end(ap);return 0;}filwrite(char*ft,...)
{va_list ap;va_start(ap,ft);void*p;char*ift=ft;int i;for
(;*ft;ft++)switch(*ft){case' ':continue;case'S':p=va_arg
(ap,char*);fputs((char*)p,ofl__);break;case'd':p=va_arg
(ap,int);fprintf(ofl__,"%d\n",(int)p);break;case'l':fprintf
(ofl__,"%ld\n",va_arg(ap,long int));break;case'L':fprintf
(ofl__,"%lld\n",va_arg(ap,long long 
int));break;case'n':i=va_arg(ap,int);if(*++ft=='D')for
(p=va_arg(ap,int*);i--;p=(int*)p+1)fprintf(ofl__,i?"%d ":
"%d\n",*(int*)p);else if(*ft=='l') for(p=va_arg(ap,long 
int*);i--;p=(long int*)p+1)fprintf(ofl__,i?"%ld ":"%ld\n",*
(long int*)p);else if(*ft=='L')for(p=va_arg(ap,long long 
int*);i--;p=(long long int*)p+1)fprintf(ofl__,i?"%lld ":
"%lld\n",*(long long int*)p);else goto 
fterror;break;default:goto fterror;fterror:fprintf
(stderr,"Error in format specifier at position %d\n",ft-
ift);va_end(ap);return 1;}va_end(ap);return 0;}
int nk,mk;long int a[17][17];int n,m;long int sumup(){long 
int sum=0,i,j;for(j=n;j--;)for(i=m;i--;)sum+=a[j][i]*(
!!(nk&1<<j)^!!(mk&1<<i)?-1:1);return sum;}main(){bothopen
("flip");filread("dd",&n,&m);int i;long int sum = 0,temp;for
(i=n;i--;)filread("Nl",&m,a[i]);for(nk=0;;nk++){for(mk=0;;mk++)
{temp=sumup(),sum<temp?sum=temp:0;if(mk==~(~0>>m<<m))break;}if
(nk==~(~0>>n<<n))break;}filwrite("l",sum);bothclose();}