#include <stdio.h>

#define IN  "flip.in"
#define OUT "flip.out"

FILE *in,*out;

int n,m,t[16][16],i,j,S,S2;

unsigned k,_1;


int main(void)
{
	_1=-1;
	if((in=fopen(IN,"rb")) == 0)
		return -1;
	if((out=fopen(OUT,"wb")) == 0)
		return -1;
	
	fscanf(in,"%d %d\n",&n,&m);
	
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			fscanf(in,"%d",&t[i][j]);	
	k=1;
	while(k != 0) {
		k=0;
		
		for(i=1;i<=n;i++) {
			S=0;S2=0;
			for(j=1;j<=m;j++) {
				S=S+t[i][j];
				S2=S2+t[i][j]*_1;
			}
			if(S2 > S) {
				k=1;
				for(j=1;j<=m;j++)
					t[i][j]*=_1;
			}
		}

		for(i=1;i<=m;i++) {
			S=0;S2=0;
			for(j=1;j<=n;j++) {
				S=S+t[j][i];
				S2=S2+t[j][i]*_1;
			}
			if(S2 > S) {
				k=1;
				for(j=1;j<=n;j++)
					t[j][i]*=_1;
			}
		}
	}
	
	S=0;
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			S+=t[i][j];
	if(S < 0)
		S=S*_1;
	fprintf(out,"%d",S);
	
	fclose(in);fclose(out);
	return 0;
}