#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

int main() {
    int n, m;
    cin >> n >> m;
    vector<ll> v(n);
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            ll x; scanf("%lld", &x);
            v[i] += x;
        }
    }
    ll a = 0, b = -INF<ll>;
    for (int i = 0; i < n; ++i) {
        ll aa = max(a, b-v[i]), bb = max(b, a+v[i]);
        swap(a, aa); swap(b, bb);
    }
    cout << max(a, b) << "\n";
    return 0;
}