#include <cstdio>
FILE *f = fopen("flip.in","r");
FILE *g = fopen("flip.out","w");

int m,n,a[17][17];
long long sum_l[17],sum_c[17],sum;

void citire(){
	
	fscanf(f,"%d%d",&n,&m);
	int i,j;
	for(i=0;i<n;i++)
		for(j=0;j<m;j++){
			
			fscanf(f,"%d",&a[i][j]);
			sum_l[i]+=a[i][j];
			sum_c[j]+=a[i][j];
			sum+=a[i][j];
		}
	fclose(f);
}

void solve(){
	
	int i,j;
	for(i=0;i<n;i++)
		if(sum_l[i]<0){
			
			sum-=sum_l[i];
			sum_l[i] = -sum_l[i];
			sum+=sum_l[i];
		}
	for(i=0;i<m;i++)
		if(sum_c[i]<0){
			
			sum-=sum_c[i];
			sum_c[i] = -sum_c[i];
			sum+=sum_c[i];
		}
}

void afis(){
	
	fprintf(g,"%lld",sum);
	fclose(g);
}

int main(){
	
	citire();
	solve();
	afis();
	return 0;
}