#include <bits/stdc++.h>
            #include<iostream>
            #include<cstdio>
            #include<vector>
            #include<queue>
            #include<map>
            #include<cstring>
            #include<string>
            #include <math.h>
            #include<algorithm>
        //    #include <boost/multiprecision/cpp_int.hpp>
            #include<functional>
     #define int long long
            #define mod  1000000007
            #define pa pair<int,int>
            #define ll long long
            #define pal pair<double,int>
            #define ppa pair<int,pa>
            #define ssa pair<string,int>
            #define  mp make_pair
            #define  pb push_back
            #define EPS (1e-10)
            #define equals(a,b) (fabs((a)-(b))<EPS)
     
            using namespace std;
     //priority_queue<int, vector<int>, greater<int> > que;
            class Point{
            	public:
            	double x,y;
            	Point(double x=0,double y=0):x(x),y(y) {}
            	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
            	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
            	Point operator * (double a) {return Point(x*a,y*a);}
            	Point operator / (double a) {return Point(x/a,y/a);}
            	double absv() {return sqrt(norm());}
            	double norm() {return x*x+y*y;}
            	bool operator < (const Point &p) const{
            		return x != p.x ? x<p.x: y<p.y;
            	}
            	bool operator == (const Point &p) const{
            		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
            	}
            };
            typedef Point Vector;
     
            struct Segment{
            Point p1,p2;
            };
     
        double hen(Vector a){
        if(fabs(a.x)<EPS && a.y>0) return acos(0);
        else if(fabs(a.x)<EPS && a.y<0) return 3*acos(0);
        else if(fabs(a.y)<EPS && a.x<0) return 2*acos(0);
        else if(fabs(a.y)<EPS && a.x>0) return 0.0;
        else if(a.y>0) return acos(a.x/a.absv());
        else return 2*acos(0)+acos(-a.x/a.absv());
     
        }
     
string itos( int i ) {
ostringstream s ;
s << i ;
return s.str() ;
}

int gcd(int v,int b){
	if(v>b) return gcd(b,v);
	if(v==b) return b;
	if(b%v==0) return v;
	return gcd(v,b%v);
}
            double dot(Vector a,Vector b){
            	return a.x*b.x+a.y*b.y;
            }
            double cross(Vector a,Vector b){
            	return a.x*b.y-a.y*b.x;
            }
        
double distans(double x1,double y1,double x2,double y2){
	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
	return sqrt(rr);
	
}
 
int beki(int a, int r){
	if(r==0)return 1;
	if(r==1) return a%mod; 
	if(r%2==1){
		int y=beki(a,r-1);
		return(y*a)%mod;
		
	}
	int yy=beki(a,r/2);
	return (yy*yy)%mod;
}
 
 int inf=mod*2;
 /*
 int kai[100000];
 int inv[100000];
int memo[1004][1004]={0};
*/
            //----------------kokomade tenpure------------
int N=262144;
pa sgt[530000];

pa minis(int i,int j ){
if(i==j) return sgt[i];
	else if(i%2==1){
		pa z=minis(i+1,j);
		if(sgt[i].first>z.first)return sgt[i] ;
		else return z;
	}
		else if(j%2==0) 	{
		pa z=minis(i,j-1);
		if(sgt[j].first>z.first)return sgt[j] ;
		else return z;
	}
else return minis(i/2,j/2);
}

pa sgtmin(int i ,int j) {
	return minis(i+N,j+N);
}

void upd(int x,int y){
	x+=N;
sgt[x].first=y;
	sgt[x].second=x;
x=x/2;
while(x != 0){
	if(sgt[2*x+1].first>sgt[2*x].first){
		sgt[x]=sgt[2*x+1];
	}
	else sgt[x]=sgt[2*x];

x=x/2;
}
}
int n,m;
int dis[6000];
int b[5010][210];
int imo[5010][5010]={0};


void saiki(int r, int l){
	if(r>l) return;
	pa zz=sgtmin(r,l);
	int k=zz.second,q=zz.first;
	
	imo[r][k]+=q;
	imo[k+1][l+1] +=q;
	imo[k+1][k]-=q;
	imo[r][l+1]-=q;
	
//	cout<<r<<" "<<l<<" "<<k<<endl;
	if(r==l) return;
	
	saiki(r,k-1);
	saiki(k+1,l);
	
}
    signed  main(){
    	for(int i=N;i<2*N;i++) sgt[i]=make_pair(0,i-N);
	dis[1]=0;
    	cin>>n>>m;
    	for(int i=2;i<=n;i++){
    		int rr;
    		cin>>rr;
    		dis[i]=dis[i-1]+rr;
    	}
    	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++) cin>>b[i][j];
    	
    	for(int iy=1;iy<=m;iy++){
    //		cout<<iy<<endl;
    		for(int i=1;i<=n;i++){
    			sgt[N+i].first=b[i][iy];
    		}
    		for(int i=N-1;i>0;i--){
				if(sgt[2*i].first<sgt[2*i+1].first) sgt[i]=sgt[2*i+1];
				else sgt[i]=sgt[2*i];
			}
    		
    		saiki(1,n);
    		
    	}
    	
    	
    	for(int j=1;j<=n+1;j++){
    		for(int i=1;i<=n+1;i++) imo[i][j] += imo[i-1][j];
    	}
		
    	for(int i=1;i<=n+1;i++){
    		for(int j=1;j<=n+1;j++) imo[i][j] += imo[i][j-1];
    	}
    	int ans=0;
    	for(int i=1;i<=n;i++)for(int j=i;j<=n;j++){
	//		cout<<"  "<<i<<" "<<j<<" "<<imo[i][j]<<endl;
    		ans=max(ans,imo[i][j]-dis[j]+dis[i]);
    	}
    	cout<<ans<<endl;
    //	cout<<memo[b][n]%mod<<endl;
    	return 0;
    }
    //printf("%d %.10f %.10f\n",i,xx/ri,yy/ri);

Measured memory_bytes: 212480