#include <iostream>
#include <vector>

using ll = long long;

ll chmax(ll &x, const ll &y){
	if(x < y) x = y;
	return x;
}

int main(){
	int n, m;
	std::cin >> n >> m;
	std::vector<ll> a(n, 0);
	for(int i = 0; i < n; ++i){
		for(int j = 0; j < m; ++j){
			ll tmp;
			std::cin >> tmp;
			a[i] += tmp;
		}
	}
	std::vector<ll> plus(n + 1, 0), minus(n + 1, 0);
	ll ans = 0;
	for(int i = 0; i < n; ++i){
		chmax(ans, chmax(plus[i + 1], minus[i] + a[i]));
		chmax(ans, chmax(minus[i + 1], plus[i] - a[i]));
	}
	std::cout << ans << std::endl;
}