#include<stdio.h>
#include<stdlib.h>

short n,m,i,j; long s,a[16][16],line[16],col[16];

int main(){
    FILE*f=fopen("flip.in","r");
    FILE*g=fopen("flip.out","w");
    fscanf(f,"%hd %hd",&n,&m);
    for(short i=0;i<n;i++)
        for(short j=0;j<m;j++){
            fscanf(f,"%ld",&a[i][j]);
            line[i]+=a[i][j];
            col[j]+=a[i][j];
        }
    for(short i=0;i<m;i++){
        if(col[i]<0){
            col[i]*=-1;
            for(short j=0;j<n;j++){
                line[j]-=a[j][i];
                a[j][i]*=-1;
                line[j]+=a[j][i];
            }
        }
    }
    for(short i=0;i<n;i++){
        if(line[i]<0){
            line[i]*=-1;
            for(short j=0;j<m;j++){
                col[j]-=a[i][j];
                a[i][j]*=-1;
                col[j]+=a[i][j];
            }
        }
    }
    for(short i=0;i<n;i++)
        s+=line[i];
    fprintf(g,"%ld",s);
    fclose(f);
    fclose(g);
    return 0;
}