#include<stdio.h>
int main () {
	int n,m,w[16][16],i,j,k,s=0,x=0,v[16][16],max=0,c;
	FILE *in=fopen("flip.in","r"), *out=fopen("flip.out","w");
	fscanf(in,"%d%d",&n,&m);
	for(i=0;i<n;i++)
		for(j=0;j<m;j++){
			fscanf(in,"%d",&w[i][j]);
			v[i][j]=w[i][j];
			s+=w[i][j];
		}
	while(s){
		for(i=0;i<n;i++){
			for(j=0;j<m;j++)
				v[i][j]*=-1;
			for(j=0;j<n;j++)
				for(k=0;k<m;k++)
					x+=v[j][k];
			if(max<x){
				max=x;
				c=i;
			}
			for(j=0;j<m;j++)
				v[i][j]*=-1;
			x=0;
		}
		for(i=0;i<m;i++)
			w[i][c]*=-1;
		if(x>s)
			s=x;
		else{
			fprintf(out,"%d\n",s);
			fclose(in);
			fclose(out);
			return 0;
		}
	}
	fclose(in);
	fclose(out);
	return 0;
}