#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif

#include<stdio.h>
#include<stdlib.h>
int main(){
	FILE *in=fopen ("flip.in","r" );
	int a[17][17],i,j,ret,aux,row=0,col=0,sum_poz,sum_neg,m,n;
	
	ret=fscanf(in,"%d %d", &m,&n);
	char *buffer=(char*)malloc(m*n*sizeof(int));
	fread(buffer,m*n*sizeof(int),1,in);
	fclose(in);
	for (i=1;i<=m*n;i++){
		sscanf(buffer,"%d",&aux);
		a[row][col]=aux;
		col++;
		if (i%m==0){
			col=0;
			row++;
		}
	}

	for (i=0;i<n;i++){
		sum_poz=0;
		sum_neg=0;
		for (j=0;j<m;j++){
			sum_poz+=a[i][j];
			sum_neg-=a[i][j];
		}
		if (sum_neg>sum_poz)
			for (j=0;j<m;j++)
				a[i][j]=-a[i][j];
	}

	sum_poz=0;
	FILE *out=fopen ("flip.out","w" );
	for (i=0;i<n;i++)
		for (j=0;j<m;j++)
			sum_poz+=a[i][j];
	
	fprintf(out, "%d", sum_poz);
	fclose(out);
	return 0;
}