//https://atcoder.jp/contests/arc067/tasks/arc067_d
/*
* Author : MaxSally
*/
/********   All Required Header Files ********/
#include<bits/stdc++.h>
using namespace std;
/*******  All Required define Pre-Processors and typedef Constants *******/
#define SCD(t) scanf("%d",&t)
#define SCLD(t) scanf("%ld",&t)
#define SCLLD(t) scanf("%lld",&t)
#define SCC(t) scanf("%c",&t)
#define SCS(t) scanf("%s",t)
#define SCF(t) scanf("%f",&t)
#define SCLF(t) scanf("%lf",&t)
#define mem(a, b) memset(a, (b), sizeof(a))
#define rep(i, j, k) for (int i = j ; i <= k ; ++i)
#define rrep(i, j, k) for (int i = j; i >= k; --i)
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define foreach(i, a) for(auto i: a)
#define forEach(it, l) for (auto it = l.begin(); it != l.end(); it++)
#define in(A, B, C) assert( B <= A && A <= C)
#define mp make_pair
#define pb push_back
#define inf (int) (1e9 + 7)
#define epsi 1e-9
#define PI 3.1415926535897932384626433832795
#define mod 1000000007
#define read(type) readInt<type>()
#define io ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long int
#define left tuyiuoi
#define right fgjhk
#define ss second
#define ff first
#define debug(a) cout << #a << ": " << a << endl
#define debuga1(a, l, r) rep(i, l, r) cout << a[i] << " "; cout << endl
#define Flag(n) cout << "here " << n << endl
const double pi=acos(-1.0);
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> vll;
typedef pair<ll, ll> pll;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<pll> vpll;
typedef vector<vi> vvi;
typedef map<int,int> MPII;
typedef set<int> SETI;
typedef multiset<int> MSETI;
typedef long int int32;
typedef unsigned long int uint32;
typedef long long int int64;
typedef unsigned long long int  uint64;

const int N = 5005;
const int M = 205;
int n, m;
ll sum[N][N], dist[N], b[N][M], left[N], right[N], s[N];

void computeSum(){
    rep(i, 1, m){
        mem(left, 0);
        mem(right, 0);
        int top = 0;
        s[top] = 0;
        rep(j, 1, n){
            while(top && b[j][i] > b[s[top]][i]){
                top--;
            }
            left[j] = s[top] + 1;
            top++;
            s[top] = j;
        }

        top = 0;
        s[top] = n + 1;
        rrep(j, n, 1){
            while(top && b[j][i] > b[s[top]][i]){
                top--;
            }
            right[j] = s[top] - 1;
            top++;
            s[top] = j;
        }

        rep(j, 1, n){
            sum[left[j]][j] += b[j][i];
            sum[j + 1][j] -= b[j][i];
            sum[left[j]][right[j] + 1] -= b[j][i];
            sum[j + 1][right[j] + 1] += b[j][i];
        }
    }
}

int main(){
    io;
    //freopen("input.txt", "r", stdin);
    cin >> n >> m;
    rep(i, 2, n){
        int x; cin >> x;
        dist[i] = dist[i - 1] + x;
    }
    rep(i, 1, n){
        rep(j, 1, m){
            cin >> b[i][j];
        }
    }
    computeSum();
    ll ans = 0;
    rep(i, 1, n){
        rep(j, 1, n){
            sum[i][j] += sum[i - 1][j] + sum[i][j - 1] - sum[i - 1][j - 1];
            if(i <= j){
                ans = max(ans, sum[i][j] + dist[i] - dist[j]);
            }
        }
    }
    cout << ans;
    return 0;
}



Measured memory_bytes: 203904