#pragma GCC optimize("O3")
#include <bits/stdc++.h> 
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
//const ll mod=998244353;
const ll mod=1000000007;
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
ll dp[1005][1005];
bool used[1005][1005]={};
int main(){
  int n,m;
  cin>>n>>m;
  V<V<ll>> a(n,V<ll>(m));
  V<ll> res(n);
  for(int i=0;i<n;i++){
      ll sum=0;
      ll val;
      for(int j=0;j<m;j++){
          cin>>val;
          sum+=val;
      }
      res[i]=sum;
  }
  for(int i=0;i<=n;i++)for(int j=0;j<=n;j++)dp[i][j]=-inf;
  dp[0][0]=0;
  used[0][0]=true;
  for(int i=0;i<n;i++){
      for(int j=n-1;j>=0;j--){
          if(!used[i][j])continue;
           chmax(dp[i+1][j+1],dp[i][j]+res[i]*(j%2==0?1ll:-1ll));
           used[i+1][j+1]=true;
           chmax(dp[i+1][j],dp[i][j]);
           used[i+1][j]=true;
      }
  }
  ll ans=0;
  for(int i=0;i<=n;i++)chmax(ans,dp[n][i]);
  cout<<ans<<"\n";
}