# include <stdio.h>
long int r,c,i,h,suma_finala=0;
long int tabel[32][32];
int citire(void)
{
    for(i=1;i<=r;i++)
    {
         for(h=1;h<=c;h++)
         {
             scanf("%d", &tabel[i][h]);
         }
    }
}
int comutare_randuri(void)
{
    long int suma;
    for(i=1;i<=r;i++)
    {
        suma = 0;
        for(h=1;h<=c;h++)
             suma += tabel[i][h];               
        if(suma < 0)
             for(h=1;h<=c;h++)
                  tabel[i][h] = tabel[i][h] * -1;
                  
    }   
}
int comutare_coloane(void)
{
    long int suma_temp;
    for(h=1;h<=c;h++)
    {
        suma_temp = 0;
        for(i=1;i<=r;i++)
             suma_temp = suma_temp + tabel[i][h];
        if(suma_temp < 0)
              suma_temp = suma_temp * -1;
        suma_finala = suma_finala + suma_temp;
    }
}
int main(void)
{
    freopen("flip.in","r",stdin);
    freopen("flip.out","w",stdout);
    scanf("%d %d", &r, &c);
    citire();
    comutare_randuri();
    comutare_coloane();
    printf("%d\n", suma_finala);
    return 0;
}