#include <bits/stdc++.h>
using namespace std;
/* typedef */
typedef long long ll;
typedef pair<int, int> pii;
/* constant */
const int INF = 1 << 30;
const ll LINF = 1LL << 50;
const int NIL = -1;
const int MAX = 10000;
const int mod = 1000000007;
const double pi = 3.141592653589;
/* global variables */
/* function */
/* main */
int main(){
    int N, M;
    cin >> N >> M;
    vector<ll> happinessDegrees(N, 0LL);
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            ll hp; cin >> hp;
            happinessDegrees[i] += hp;
        }
    }

    vector<ll> dp(N+1, -LINF);  // N個選んだときのMax
    dp[0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j <= i; j++) {
            dp[j + 1] = max(dp[j + 1], dp[j] + happinessDegrees[i] * (j % 2 ? -1 : 1));
        }
    }
    cout << *max_element(dp.begin(), dp.end()) << '\n';
}