#include<stdio.h>

int main(){
    
    long m[16][16], v[16],w[16],s=0;
    int i,j,N,M;
    FILE *fp;
    
    fp=fopen("flip.in", "r");
    fscanf(fp, "%d %d", &N, &M);
    
    for (i=1;i<=N;i++)
        v[i]=0;
    for (i=1;i<=M;i++)
        w[i]=0;
    
    for (i=1;i<=N;i++){
        for (j=1;j<=M;j++){
            fscanf(fp, "%ld", &m[i][j]);
                v[i]+=m[i][j];
                w[j]+=m[i][j];              
        }
    }
    fclose(fp);
    for (i=1;i<=N;i++){
        if (v[i]<0){
           for (j=1;j<=M;j++){                          
               m[i][j]=m[i][j]*(-1);
           }
        }
    }
    for (i=1;i<=M;i++){
        if (w[i]<0){
           for (j=1;j<=N;j++){                          
               m[j][i]=m[j][i]*(-1);
           }
        }
    }
    for (i=1;i<=N;i++){
        for (j=1;j<=M;j++){
            s+=m[i][j];
        }
    }
    fp=fopen("flip.out", "w");
    fprintf(fp, "%ld", s);
    fclose(fp);

}