#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int(i) = 0; (i) < (n); (i)++)
#define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++)
#define All(v) (v).begin(), (v).end()
#define pb push_back
#define MP(a, b) make_pair((a), (b))
template <class T> vector<T> make_vec(size_t a, T val) {
    return vector<T>(a, val);
}
template <class... Ts> auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec(ts...))>(a, make_vec(ts...));
}
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using Graph = vector<vector<int>>;
template <typename T> struct edge {
    int to;
    T cost;
    edge(int t, T c) : to(t), cost(c) {}
};
template <typename T> using WGraph = vector<vector<edge<T>>>;
const int INF = 1 << 30;
const ll LINF = 1LL << 60;
const int MOD = 1e9 + 7;

int main() {
    int N, M;
    cin >> N >> M;
    vector<vector<ll>> A(N, vector<ll>(M));
    rep(i, N) {
        rep(j, M) { cin >> A[i][j]; }
    }
    vector<ll> B(N);
    rep(i, N) {
        rep(j, M) { B[i] += A[i][j]; }
    }
    auto dp = make_vec(N + 1, N + 1, 0LL);
    // dp[i][j]:=i-1個目まで見て、j個食べたときの最大
    for(int i = 0; i < N; i++) {
        for(int j = 0; j <= i; j++) {
            if(j % 2 == 0) {
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + B[i]);
            } else {
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] - B[i]);
            }
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
        }
    }
    ll res = 0;
    rep(i, N + 1) res = max(res, dp[N][i]);
    cout << res << endl;
}