#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
constexpr ll INF = (1LL << 60);
int main(){ 
  int n, m;
  cin >> n >> m;
  vector<ll> a(n, 0);
  rep(i,n) {
    rep(j,m) {
      ll b;
      cin >> b;
      a[i] += b;
    }
  }
  
  vector<vector<ll>> dp(n + 1, vector<ll>(2, 0));
  ll res = 0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= i; j++) {
      dp[i + 1][0] = max(dp[i + 1][0], dp[j][1] + a[i]);
      dp[i + 1][1] = max(dp[i + 1][1], dp[j][0] - a[i]);
    }
    res = max(dp[i + 1][0], res);
    res = max(dp[i + 1][1], res);
  }

  cout << res << endl;
  return 0; 
}