#include <bits/stdc++.h>
#include <unistd.h>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
 
 
typedef long long ll;
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
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; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
//const ll MOD = 1000000007;
const ll MOD = 998244353;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { -1,0, 1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
// #define mp make_pair
//#define endl '\n'


template <typename T>
class SegmentTree {
public:
  using F = function<T(T&, T&)>;
  int n;
  vector<T > dat;
  T e; // 単位元
  F query_func;
  F update_func;
  
  SegmentTree(vector<T> a, F query_func, F update_func, T e) :n(a.size()), query_func(query_func), update_func(update_func), e(e) {
    dat.resize(4 * n);
    init(0, 0, n, a);
  }

  void init(int k, int l, int r, vector<T> &a) {
    if (r - l == 1) {
      dat[k] = a[l];
    }
    else {
      int lch = 2 * k + 1, rch = 2 * k + 2;
      init(lch, l, (l + r) / 2, a);
      init(rch, (l + r) / 2, r, a);
      dat[k] = query_func(dat[lch], dat[rch]);
    }
  }

  //k番目の値をaに変更
  void update(int k, T a, int v, int l, int r) {
    if (r - l == 1) {
      dat[v] = update_func(dat[v], a);
    }
    else {
      if (k < (l + r) / 2)
        update(k, a, 2 * v + 1, l, (l + r) / 2);
      else {
        update(k, a, 2 * v + 2, (l + r) / 2, r);
      }
      dat[v] = query_func(dat[v * 2 + 1], dat[v * 2 + 2]);
    }
  }
    

  //[a,b)の最小値を求める
  //後ろのほうの引数は計算の簡単のための引数
  //kは接点の番号,l,rはその接点が[l,r)に対応していることを表す
  //従って、外からはquery(a,b,0,0,n)としてよぶ
  T query(int a, int b, int k, int l, int r) {
    if (r <= a || b <= l) {
      return e;
    }
    if (a <= l && r <= b) {
      return dat[k];
    }
    else {
      T ul = query(a, b, k * 2 + 1, l, (l + r) / 2);
      T ur = query(a, b, k * 2 + 2, (l + r) / 2, r);
      return query_func(ul, ur);
    }
  }
};

pll f1(pll a, pll b) {return max(a, b);}

ll res[5001][5001];

void solve(SegmentTree<pll>& seg, int l, int r) {
  pll mi = seg.query(l, r, 0, 0, seg.n);
  ll m = mi.second;
  ll x = mi.first;
  //DEBUG(pll(l, r));
  //DEBUG(pll(m, x));
  
  res[l][m] += x;
  res[l][r] -= x;
  res[m + 1][m] -= x;
  res[m + 1][r] += x;
  if (l != m) {
    solve(seg, l, m);
  }
  if (m + 1 != r) {
    solve(seg, m + 1, r);
  }
}

int main() {
  int n, m;
  cin >> n >> m;
  vl x(n);
  rep (i, n - 1) {
    ll diff;
    cin >> diff;
    x[i + 1] = x[i] + diff;
  }

  vll b(n, vl(m));
  rep (i, n) {
    rep (j, m) {
      cin >> b[i][j];
    }
  }

  rep (i, m) {
    vector<pll> temp(n);
    rep (j, n) temp[j] = pll(b[j][i], j);
    SegmentTree<pll> seg(temp, f1, f1, pll(-INF, -INF));
    solve(seg, 0, n);

    // rep (i, n + 1) {
    //   rep (j, n) {
    //     res[i][j + 1] += res[i][j];
    //   }
    //   if (i != 0) {
    //     rep (j, n + 1) {
    //       res[i][j] += res[i - 1][j];
    //     }
    //   }
    // }
    
    
    // rep (i, 4) {
    //   rep (j, 4) {
    //     cout << res[i][j] << " ";
    //   }
    //   cout << endl;
    // }
    
  }

  
  rep (i, n + 1) {
    rep (j, n) {
      res[i][j + 1] += res[i][j];
    }
    if (i != 0) {
      rep (j, n + 1) {
        res[i][j] += res[i - 1][j];
      }
    }
  }

  // rep (i, 4) {
  //   rep (j, 4) {
  //     cout << res[i][j] << " ";
  //   }
  //   cout << endl;
  // }

  
  
  ll ma = 0;
  rep (i, n) {
    for (int j = i; j < n; j++) {
      chmax(ma, res[i][j] - (x[j] - x[i]));
    }
  }
  cout << ma << endl;
}


Measured memory_bytes: 204228