#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("flip.in");
ofstream fout("flip.out");

int v[17][17];
int n, m;

void read() {
    fin >> n >> m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) {
            fin >> v[i][j];
            v[i][0] += v[i][j];
            v[0][j] += v[i][j];
            v[0][0] += v[i][j];
        }
}

void flipLine(int line) {
    for (int i = 1; i <= n; i++) {
        v[line][i] *= -1;
        v[0][i] += 2 * v[line][i];
    }
    v[line][0] *= -1;
    v[0][0] += 2 * v[line][0];
}

void flipColumn(int column) {
    for (int i = 1; i <= m; i++) {
        v[i][column] *= -1;
        v[i][0] += 2 * v[i][column];
    }
    v[0][column] *= -1;
    v[0][0] += 2 * v[0][column];
}

void getMaxOnCL(int line[], int l, int column[], int c, int poz, int &max){
    if(poz<=l+c) {
        if (v[0][0] > max)
            max = v[0][0];
        getMaxOnCL(line, l, column, c, poz + 1, max);
        if (poz <= l) {
            flipLine(line[poz]);
        } else if (poz <= l + c) {
            flipColumn(column[poz - l]);
        }
        if (v[0][0] > max)
            max = v[0][0];
        getMaxOnCL(line, l, column, c, poz + 1, max);
    }
}

int getMax() {
    bool ok;
    do {
        ok = false;
        for (int i = 1; i <= n; i++)
            if (v[i][0] < 0) {
                flipLine(i);
                ok = true;
            }
        for (int j = 1; j <= m; j++)
            if (v[0][j] < 0) {
                flipColumn(j);
                ok = true;
            }
    } while (ok);

    int line[16], l=0;
    for(int i=1; i<=n; i++)
        if(v[i][0] == 0) line[++l]=i;

    int column[16], c=0;
    for(int i=1; i<=m; i++)
        if(v[0][i]==0) column[++c]=i;
    int max=v[0][0];
    getMaxOnCL(line, l, column, c, 1, max);
    return max;
}

int main() {
    read();
    fout << getMax();
}