#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';
constexpr ll INF = 1e18;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    ll dpo = -INF, dpe = 0;
    for (int i = 0; i < n; i++) {
        ll sum = 0;
        for (int j = 0; j < m; j++) {
            ll a;
            cin >> a;
            sum += a;
        }

        ll ndpo = max(dpo, dpe + sum);
        ll ndpe = max(dpe, dpo - sum);
        dpo = ndpo;
        dpe = ndpe;
    }
    cout << max(dpo, dpe) << newl;

    return 0;
}