#include <bits/stdc++.h>
#define NMAX 100
using namespace std;

fstream f("in.txt");

int n,m;
int v[NMAX][NMAX];
bool sol[NMAX*2];
int maxim = INT_MIN;

int sumMat();
void bkt(int);

int main(){
    cin >> n >> m;
    for(int i = 0; i < n;++i){
        for(int j = 0;j < m;++j)
            cin >> v[i][j];
    }

    bkt(0);

    cout << maxim;
    return 0;
}
int sumMat(){

    int s = 0;

    for(int i = 0;i < n;++i){
        for(int j = 0; j < m;++j){

            if(sol[i])
                v[i][j] *= -1;
            if(sol[n + j - 1])
                v[i][j] *= -1;

            s += v[i][j];

            if(sol[n + j - 1])
                v[i][j] *= -1;
            if(sol[i])
                v[i][j] *= -1;
        }
    }
    return s;
}
void bkt(int k){
    if(k == m + n){
        maxim = max(maxim, sumMat());
    }else{
        for(int i = 0; i <= 1; ++i){
            sol[k] = bool(i);
            bkt(k + 1);
        }
    }
}