/*

                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                    prayer
*/

// g++ -std=c++11 a.cpp
#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<unordered_map>
#include<utility>
#include<cmath>
#include<random>
#include<cstring>
#include<queue>
#include<stack>
#include<bitset>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#include<typeinfo>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define FOR(i,a) for(auto i:a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
#define show1d(v) rep(_,v.size())cout<<" "<<v[_];cout<<endl;
#define show2d(v) rep(__,v.size()){rep(_,v[__].size())cout<<" "<<v[__][_];cout<<endl;}
using namespace std;
//kaewasuretyuui
typedef long long ll;
#define int ll
typedef int Def;
typedef pair<Def,Def> pii;
typedef vector<Def> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<Def,pii> pip;
typedef vector<pip>vip;
// #define mt make_tuple
// typedef tuple<int,int,int> tp;
// typedef vector<tp> vt;
template<typename A,typename B>bool cmin(A &a,const B &b){return a>b?(a=b,true):false;}
template<typename A,typename B>bool cmax(A &a,const B &b){return a<b?(a=b,true):false;}
//template<class C>constexpr int size(const C &c){return (int)c.size();}
//template<class T,size_t N> constexpr int size(const T (&xs)[N])noexcept{return (int)N;}
const double PI=acos(-1);
const double EPS=1e-9;
Def inf = sizeof(Def) == sizeof(long long) ? 2e18 : 1e9+10;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};

typedef pii SegT;
const SegT defvalue={-inf,-inf};
class SegTree{
	private:
		vector<SegT>val;
		int n;
		SegT combine(SegT a,SegT b){return a>b?a:b;}
	public:
		SegTree(){}
		SegTree(int size){
			n=1;
			while(n<size)n<<=1;
			val=vector<SegT>(2*n,defvalue);
		}
		SegTree(const vector<int> &in){
			n=1;
			while(n<in.size())n<<=1;
			val=vector<SegT>(2*n,defvalue);
			for(int i=n-1+in.size()-1;i>=0;i--){
				if(n-1<=i)val[i]=pii{in[i-(n-1)],i-(n-1)};
				else val[i]=combine(val[i*2+1],val[i*2+2]);
			}
		}
		SegT query(int a,int b,int k=0,int l=0,int r=-1){//[a,b)
			if(r==-1)r=n;
			if(r<=a||b<=l)return defvalue;
			if(a<=l&&r<=b)return val[k];
			else return combine(query(a,b,k*2+1,l,(l+r)/2),query(a,b,k*2+2,(l+r)/2,r));
		}
};
int n,m;
vvi in;
vvi dp;
SegTree st;
void f(int l,int r,int c){
	if(l>=r)return;
	pii t=st.query(l,r);
	c+=t.first;
	dp[l][l]+=c;
	dp[l][r]-=c;
	dp[r][l]-=c;
	dp[r][r]+=c;
	f(l,t.second,-t.first);
	f(t.second+1,r,-t.first);
}
signed main(){
	cin>>n>>m;
	vi dist(n);
	rep(i,n-1)cin>>dist[i+1];
	rep(i,n-1)dist[i+1]+=dist[i];
	in=vvi(m,vi(n));
	dp=vvi(n+1,vi(n+1));
	rep(i,n)rep(j,m)cin>>in[j][i];
	rep(i,m){
		st=SegTree(in[i]);
		f(0,n,0);
	}
	// show2d(in);
	rep(i,n+1)rep(j,n)dp[i][j+1]+=dp[i][j];
	rep(i,n)rep(j,n+1)dp[i+1][j]+=dp[i][j];
	// show2d(dp);
	int out=0;
	rep(i,n)loop(j,i,n)cmax(out,dp[i][j]-(dist[j]-dist[i]));
	cout<<out<<endl;
}















Measured memory_bytes: 204288