#include <iostream>
#include <vector>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
using ll = long long;

const ll INF = 3e18;

int main() {
    int n, m;
    cin >> n >> m;
    vector<ll>a(n);
    rep(i, n) {
        ll cnt = 0;
        rep(j, m) {
            ll x;
            cin >> x;
            cnt += x;
        }
        a[i] = cnt;
    }
    vector<vector<ll>> dp(n + 1, vector<ll>(2, -INF));
    dp[0][0] = 0;
    for (int i = 1; i <= n; i++) {
        rep(j, i) {
            rep(k, 2) {
                if (k == 0) dp[i][1] = max(dp[j][k] + a[i - 1], dp[i][1]);
                if (k == 1) dp[i][0] = max(dp[j][k] - a[i - 1], dp[i][0]);
            }
        }
    }
    ll ans = -INF;
    rep(i, n + 1) {
        rep(j, 2) ans = max(ans, dp[i][j]);
    }
    cout << ans << endl;
}