#include <fstream>
#include <bitset>
using namespace std;

int main() {
    ifstream fin("flip.in");
    ofstream fout("flip.out");
    int n, m, i, j, A[17][17], s, maxx = 0, L, C;
    bitset<32> key;
    fin >> n >> m;
    for(i = 1; i <= n; ++i)
        for(j = 1; j <= m; ++j)
            fin >> A[i][j];
    for(L = 1; L < 1 << n; ++L)
        for(C = 1; C < 1 << m; ++C) {
            s = 0;
            for(i = 1; i <= n; ++i)
                for(j = 1; j <= m; ++j)
                    if((L >> (i-1)) % 2 == (C >> (j-1)) % 2)
                        s += A[i][j];
                    else
                        s -= A[i][j];
            if(s > maxx)
                maxx = s;
        }
    fout << maxx;
}