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

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

const int MAX_NUM = 16;

int n, m, a[MAX_NUM][MAX_NUM];
int maxSum = INT_MIN;

int calculateSum() {
    int sum = 0;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            sum += a[i][j];
        }
    }
    return sum;
}

void inverseRow(int row) {
    for (int j = 0; j < m; ++j) {
        a[row][j] *= -1;
    }
}

void inverseColumn(int col) {
    for (int i = 0; i < n; ++i) {
        a[i][col] *= -1;
    }
}

void maximizeSum(int row, int col) {
    if (row == n) {
        int currentSum = calculateSum();
        maxSum = max(maxSum, currentSum);
        return;
    }
    if (row < n) {
        maximizeSum(row + 1, col);
        inverseRow(row);
        maximizeSum(row + 1, col);
        inverseRow(row);
    }
    if (col < m) {
        maximizeSum(row, col + 1);
        inverseColumn(col);
        maximizeSum(row, col + 1);
        inverseColumn(col);
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    fin >> n >> m;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            fin >> a[i][j];
        }
    }
    maximizeSum(0, 0);
    fout << maxSum << "\n";
    return 0;
}