#include <stdio.h>

int N,M;
long int tabla[17][17];

long int suma_col(int i)
{
     int j, suma=0;
     for(j=0;j<N;j++)
     suma+=tabla[j][i];
     return suma;
}

long int suma_lin(int i)
{
     int j, suma=0;
     for(j=0;j<N;j++)
     suma+=tabla[i][j];
     return suma;
}

void comuta_col(int i)
{
     int j;
     for(j=0;j<N;j++)
     tabla[j][i]=(-1)*tabla[j][i];
}

void comuta_lin(int i)
{
     int j;
     for(j=0;j<N;j++)
     tabla[i][j]=(-1)*tabla[i][j];
}

int main()
{
    int suma,i,j;
    FILE *ie,*in;
    in=fopen("flip.in","r");
    fscanf(in,"%d %d",&N,&M);
    for(i=0;i<N;i++)
    for(j=0;j<M;j++)
    fscanf(in,"%ld",&tabla[i][j]);
    fclose(in);
    for(i=0;i<N;i++)
    if(suma_col(i)<0)
    comuta_col(i);
    for(i=0;i<M;i++)
    if(suma_lin(i)<0)
    comuta_lin(i);
    for(i=0;i<N;i++)
    for(j=0;j<M;j++)
    suma=suma+tabla[i][j];
    ie=fopen("flip.out","w");
    fprintf(ie,"%ld",suma);
    fclose(ie);
}