#include <iostream>
#include <vector>

using lint = long long;
constexpr lint INF = 1LL << 60;

void solve() {
    int n, m;
    std::cin >> n >> m;

    std::vector<lint> dp(2, -INF);
    dp[0] = 0;

    while (n--) {
        lint sum = 0;
        for (int i = 0; i < m; ++i) {
            lint x;
            std::cin >> x;
            sum += x;
        }

        auto ndp = dp;
        ndp[0] = std::max(ndp[0], dp[1] - sum);
        ndp[1] = std::max(ndp[1], dp[0] + sum);
        std::swap(dp, ndp);
    }

    std::cout << std::max(dp[0], dp[1]) << "\n";
}

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

    solve();

    return 0;
}