#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;
long long calcSum(vector<vector<int>> x) {
    long long sum = 0;
    int length = x.size(), length2;
    for(int i = 0; i < length; ++i) {
        length2 = x[i].size();
        for(int j = 0; j < length2; ++j)
            sum += x[i][j];
    }
    return sum;
}
void reverseLine(vector<vector<int>> &x, int line) {
    int length = x[line].size();
    for(int j = 0; j < length; ++j)
        x[line][j] *= -1;
}
void reverseCol(vector<vector<int>> &x, int col) {
    int length = x.size();
    for(int i = 0; i < length; ++i)
        x[i][col] *= -1;
}
int main()
{
    freopen("flip.in", "r", stdin);
    freopen("flip.out", "w", stdout);
    int n, m;
    cin >> n >> m;
    vector<vector<int>> x(n, vector<int>(m));
    for (int i = 0; i < n; ++i) {
        for(int j = 0; j < m; ++j)
            cin >> x[i][j];
    }
    int maxdim = m + n, max_sum = -9999999;
    long long limit = 1 << maxdim;
    for (long long i = 1; i < limit - 1; ++i)
    {
        for(int k = 0; k < 2; ++k) {
            int power = 1;
            for (int j = 0; j < maxdim; ++j)
            {
                if (i & power) {
                    if(j >= n)
                        reverseCol(x, j - n);
                    else
                        reverseLine(x, j);
                }
                power <<= 1;
            }
            if(!k) {
                int current = calcSum(x);
                if(current > max_sum)
                    max_sum = current;
            }
        }
    }
    cout << max_sum;
    return 0;
}