#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
using namespace std;
using Int = long long;
using ll = long long;
using Double = long double;
const Int INF = (1LL<<55)+1e9; // ~ 3.6 * 1e16
const Int mod = (1e9)+7;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
using P = pair<Int,Int>;
using T = tuple<Int,Int,Int>;
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
ostream& operator<<(ostream& o,P p){return o<<"("<<p.first<<","<<p.second<<")";}
ostream& operator<<(ostream& o,T t){return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
istream& operator>>(istream& i,P &p){return i>>p.first>>p.second;}
ostream& operator<<(ostream& o,vector<auto> &a){Int i=0;for(auto t:a)o<<(i++?" ":"")<<t;return o;}
istream& operator>>(istream& i,vector<auto> &a){for(auto &t:a)i>>t;return i;}
void prArr(auto a,string s=" "){Int i=0;for(auto t:a)cout<<(i++?s:"")<<t;cout<<endl;}



class Seg{
public: 
  
  
  struct T{
    bool type; //0 - empty   , 1 - update
    Int value;
    T():type(0),value(0){}
    T(bool type,Int value):type(type),value(value){}
  };

  //比較可能な主データ型
  struct D{
    Int value;
    Int idx;
    D():value(0){} /*適切な値にする!!!!!!*/
    D(Int value,Int idx):value(value),idx(idx){}
  };
  
  D INF = D(-(1LL<<55),-(1LL<<55)); /*!!!!!!!!!!!!!!!!!!!!!!!!*/
  
  Int n;
  vector<D> dat;
  vector<T> td;
  
  Seg(){n=-1;}
  Seg(Int n_){
    n=1;
    while(n<n_)n*=2;
    td.resize(2*n-1,T());
    dat.resize(2*n-1,D());
  }
  
  D merge(D a,D b){
    if(a.value < b.value) return b;
    return a;
  }
  
  void delay(Int k){
  }
  
  D update(Int k,D x){
    dat[k] = x;
    return dat[k];
  }
  
  //[a,b)の値をx加算　add(a,b,x)
  D query(Int a,Int b,D x,bool flg=true,Int k=0,Int l=0,Int r=-1){
    if(r==-1) r=n, assert(a <= n && b <= n);
    if(r<=a||b<=l) return flg? dat[k]:INF;
    if(a<=l&&r<=b) return flg? update(k,x):dat[k];
    
    delay(k);
    D vl = query(a,b,x,flg,k*2+1,l,(l+r)/2);
    D vr = query(a,b,x,flg,k*2+2,(l+r)/2,r);
    if(flg) dat[k] = merge(vl,vr);
    return merge(vl,vr);
  }
  
  //[a,b)の最小値を得る　find(a,b);
  D find(Int a,Int b){
    D res = query(a,b,{},false);
    return res;
  }
};


class CumulativeSum{
public:
  vector<Int> sum;
  CumulativeSum(){}
  CumulativeSum(vector<Int> A){
    Int n = A.size();
    sum.resize(n+1,0);
    for(Int i=1;i<=n;i++) sum[i] += sum[i-1] + A[i-1];
  }
  Int get(Int l,Int r){assert(l<=r && l>=0 && r<=(Int)sum.size());return sum[r] - sum[l];} //[l,r)
};

Int n;
vector<vector<Int> > sum;
vector<vector<Int> > Niku;

Seg S;
void dfs(Int l,Int r,Int k){
  if(l > r) return;
  Int idx = S.find(l, r+1).idx;
  {
    Int a = Niku[idx][k];
    sum[l+1][idx+1] += a;
    sum[l+1][r+1+1] -= a;
    sum[idx+1+1][idx+1] -= a;
    sum[idx+1+1][r+1+1] += a;
  }
  
  dfs(l, idx-1, k);
  dfs(idx+1, r, k);
}

signed main(){
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  Int m;
  cin>>n>>m;
  
  vector<Int> A(n);
  for(Int i=0;i<n-1;i++) cin>>A[i+1];

  S = Seg(n);
  Niku = vector<vector<Int> > (n,vector<Int>(m));
  cin>>Niku;

  sum.resize(n+2);
  for(Int i=0;i<n+2;i++) sum[i].resize(n+2); 
  
  for(Int i=0;i<m;i++) {
    for(Int j=0;j<n;j++) S.query(j, j+1,{Niku[j][i],j});
    dfs(0, n-1, i);
  }
  
  for(Int i=1;i<=n;i++)
    for(Int j=1;j<=n;j++) sum[i][j] += sum[i][j-1];
  
  for(Int j=1;j<=n;j++)
    for(Int i=1;i<=n;i++) sum[i][j] += sum[i-1][j];
  
  
  CumulativeSum Dis(A);

 Int ans = -INF;
 for(Int i=0;i<=n;i++)
   for(Int j=i;j<=n;j++) {
     Int a = sum[i][j];
     Int b = Dis.get(i, j);
     Int score = a - b;
     Max(ans, score);
   } 	
  
  cout<<ans<<endl;
  return 0;
}


Measured memory_bytes: 206592