#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>
#include <math.h>
#include <iomanip>
#include <limits>
#include <list>
#include <queue>
#include <tuple>
#include <map>
#include <stack>
#include <set>
using namespace std;
#define MOD (long long int)(1e9+7)
#define ll long long int
#define rep(i,n) for(int i=0; i<(int)(n); i++)
#define reps(i,n) for(int i=1; i<=(int)(n); i++)
#define REP(i,n) for(int i=n-1; i>=0; i--)
#define REPS(i,n) for(int i=n; i>0; i--)
#define INF (int)(1123456789)
#define LINF (long long int)(112345678901234567)
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
#define all(v) v.begin(), v.end()

const int N = (int)3e5;

ll mpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = mpow(a,b/2); return memo*memo%MOD;}
  else return mpow(a,b-1) * a % MOD;
}
ll lpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = lpow(a,b/2); return memo*memo;}
  else return lpow(a,b-1) * a;
}
ll gcd(ll a, ll b){
  if(b==0) return a;
  else return gcd(b, a%b);
}
vector<ll> kaijo_memo;
ll kaijo(ll n){
  if(kaijo_memo.size() > n) return kaijo_memo[n];
  if(kaijo_memo.size() == 0) kaijo_memo.push_back(1);
  while(kaijo_memo.size() <= n) kaijo_memo.push_back(kaijo_memo[kaijo_memo.size()-1] * kaijo_memo.size() % MOD);
  return kaijo_memo[n];
}
vector<ll> gyaku_kaijo_memo;
ll gyaku_kaijo(ll n){
  if(gyaku_kaijo_memo.size() > n) return gyaku_kaijo_memo[n];
  if(gyaku_kaijo_memo.size() == 0) gyaku_kaijo_memo.push_back(1);
  while(gyaku_kaijo_memo.size() <= n) gyaku_kaijo_memo.push_back(gyaku_kaijo_memo[gyaku_kaijo_memo.size()-1] * mpow(gyaku_kaijo_memo.size(), MOD-2) % MOD);
  return gyaku_kaijo_memo[n];
}

ll nCr(ll n, ll r){
  if(n == r) return 1;//0個の丸と-1個の棒みたいな時に時に効く？不安.
  if(n < r || r < 0) return 0;
  ll ret = 1;
  ret *= kaijo(n); ret %= MOD;
  ret *= gyaku_kaijo(r); ret %= MOD;
  ret *= gyaku_kaijo(n-r); ret %= MOD;
  return ret;
}


int main(void){
  ll n,m;cin>>n>>m;
  vector<ll> A;
  rep(i,n-1){
    ll a;
    cin>>a;
    A.push_back(a);
  }
  vector<vector<ll>> B;
  rep(i,n){
    B.push_back(vector<ll>());
    rep(j,m){
      ll b;cin>>b;
      B[i].push_back(b);
    }
  }

  vector<vector<ll>> imos;
  rep(i,n+3){
    imos.push_back(vector<ll>());
    rep(j,n+3){
      imos[i].push_back(0);
    }
  }


  rep(mi,m){
    vector<ll> values;
    values.push_back(LINF);
    rep(i,n){
      values.push_back(B[i][mi]);
    }
    values.push_back(LINF);

    vector<ll> L,R;

    L.push_back(0);
    vector<pair<ll,ll>> stack;
    stack.push_back({LINF,0});
    reps(i,n){
      while(stack.back().first < values[i]){
        stack.pop_back();
      }
      L.push_back(stack.back().second + 1);
      if(stack.back().first == values[i]){
        stack.pop_back();
      }
      stack.push_back({values[i], i});
    }

    stack.clear();
    stack.push_back({LINF,n+1});
    REPS(i,n){
      while(stack.back().first < values[i]){
        stack.pop_back();
      }
      R.push_back(stack.back().second - 1);
      if(stack.back().first == values[i]){
        stack.pop_back();
      }
      stack.push_back({values[i], i});
    }
    R.push_back(0);
    reverse(all(R));
    //前処理終わり
    //ここからいもす

    reps(i,n){
      //cout<<i<<" "<<L[i]<<" "<<R[i]<<endl;
      imos[L[i]][i] += values[i];
      imos[i+1][i] -= values[i];
      imos[L[i]][R[i]+1] -= values[i];
      imos[i+1][R[i]+1] += values[i];
    }

  }
  cerr<<endl;
  /*REP(ri,n+2){
    rep(li,n+2){
      cout<<imos[li][ri]<<" ";
    }
    cout<<endl;
  }*/
  cerr<<endl;
  rep(y,n+1){
    rep(x,n){
      imos[x+1][y] += imos[x][y];
    }
  }
  rep(x,n+1){
    rep(y,n){
      imos[x][y+1] += imos[x][y];
    }
  }

  /*REP(ri,n+2){
    rep(li,n+2){
      cout<<imos[li][ri]<<" ";
    }
    cout<<endl;
  }*/

  //ruiseki[r] - ruiseki[l]
  vector<ll> ruiseki;
  ruiseki.push_back(0);
  ruiseki.push_back(0);
  rep(i,n-1){
    ruiseki.push_back(ruiseki.back() + A[i]);
  }

  ll ans = 0;
  reps(i,n){
    reps(j,n){
      if(i > j) continue;
      chmax(ans, imos[i][j] - (ruiseki[j] - ruiseki[i]));
    }
  }
  cout<<ans<<endl;
  return 0;

}


Measured memory_bytes: 230096