#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, ll> pil;
typedef pair<int, ll> pli;
typedef pair<double,double> pdd;
#define SQ(i) ((i)*(i))
#define MEM(a, b) memset(a, (b), sizeof(a))
#define SZ(i) int(i.size())
#define FOR(i, j, k, in) for (int i=j ; i<k ; i+=in)
#define RFOR(i, j, k, in) for (int i=j ; i>=k ; i-=in)
#define REP(i, j) FOR(i, 0, j, 1)
#define REP1(i,j) FOR(i, 1, j+1, 1)
#define RREP(i, j) RFOR(i, j, 0, 1)
#define ALL(_a) _a.begin(),_a.end()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define X first
#define Y second
#ifdef tmd
#define TIME(i) Timer i(#i)
#define debug(...) do{\
    fprintf(stderr,"%s - %d (%s) = ",__PRETTY_FUNCTION__,__LINE__,#__VA_ARGS__);\
    _do(__VA_ARGS__);\
}while(0)
template<typename T>void _do(T &&_x){cerr<<_x<<endl;}
template<typename T,typename ...S> void _do(T &&_x,S &&..._t){cerr<<_x<<" ,";_do(_t...);}
template<typename _a,typename _b> ostream& operator << (ostream &_s,const pair<_a,_b> &_p){return _s<<"("<<_p.X<<","<<_p.Y<<")";}
template<typename It> ostream& _OUTC(ostream &_s,It _ita,It _itb)
{
    _s<<"{";
    for(It _it=_ita;_it!=_itb;_it++)
    {
        _s<<(_it==_ita?"":",")<<*_it;
    }
    _s<<"}";
    return _s;
}
template<typename _a> ostream &operator << (ostream &_s,vector<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s,set<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s,deque<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a,typename _b> ostream &operator << (ostream &_s,map<_a,_b> &_c){return _OUTC(_s,ALL(_c));}
template<typename _t> void pary(_t _a,_t _b){_OUTC(cerr,_a,_b);cerr<<endl;}
#define IOS()
#else
#define TIME(i)
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0)
#endif
class Timer {
private:
    string scope_name;
    chrono::high_resolution_clock::time_point start_time;
public:
    Timer (string name) : scope_name(name) {
        start_time = chrono::high_resolution_clock::now();
    }
    ~Timer () {
        auto stop_time = chrono::high_resolution_clock::now();
        auto length = chrono::duration_cast<chrono::microseconds>(stop_time - start_time).count();
        double mlength = double(length) * 0.001;
        debug(scope_name, mlength);
    }
};

const ll MOD = 1000000007;
const ll INF = 0x3f3f3f3f3f3f3f3f;
const int iNF = 0x3f3f3f3f;
const int MAXN = 5003;
const int MAXM = 202;


int n, m, a[MAXN], b[MAXN][MAXM], seg[MAXN * 2];
ll bit[MAXN][MAXN], pre[MAXN];

ll qry (int x, int _y) {
    ll ret = 0;
    x++, _y++;
    for (; x>0; x-=-x&x) {
        for (int y=_y; y>0; y-=-y&y) {
            ret += bit[x][y];
        }
    }
    return ret;
}

void add (int x, int _y, int val) {
    for (; x<MAXN; x+=-x&x) {
        for (int y=_y; y<MAXN; y+=-y&y) {
            bit[x][y] += val;
        }
    }
}

void add (int xl, int xr, int yl, int yr, int val) {
    xl++, xr++, yl++, yr++;
    add(xl, yl, val);
    add(xr+1, yl, -val);
    add(xl, yr+1, -val);
    add(xr+1, yr+1, val);
}

void build_seg () {
    for (int i=n-1; i>0; i--) {
        seg[i] = max(seg[i<<1], seg[i<<1|1]);
    }
}

int qrymx (int l, int r) {
    int mx =  0;
    for (l+=n, r+=n; l<r; l>>=1, r>>=1) {
        if (l&1) {
            mx = max(mx, seg[l++]);
        }
        if (r&1) {
            mx = max(mx, seg[--r]);
        }
    }
    return mx;
}

int search_l (int id, int val) {
    int l = -1, r = id;
    while (l < r - 1) {
        int mid = (l + r) >> 1;
        if (qrymx(mid, id) >= val) {
            l = mid;
        } else {
            r = mid;
        }
    }
    return l+1;
}

int search_r (int id, int val) {
    int l = id, r = n;
    while (l < r - 1) {
        int mid = (l + r) >> 1;
        if (qrymx(id+1, mid+1) > val) {
            r = mid;
        } else {
            l = mid;
        }
    }
    return r-1;
}
/********** Good Luck :) **********/
int main () {
    TIME(main);
    IOS();

    cin >> n >> m;
    REP1 (i, n-1) {
        cin >> a[i];
        pre[i] = pre[i-1] + a[i];
    }

    REP (i, n) {
        REP (j, m) {
            cin >> b[i][j];
        }
    }

    REP (j, m) {
        REP (i, n) {
            seg[i+n] = b[i][j];
        }
        build_seg();

        REP (i, n) {
            int l = search_l(i, b[i][j]);
            int r = search_r(i, b[i][j]);

            add(l, i, i, r, b[i][j]);
            debug(l, i, i, r, b[i][j]);
        }
    }

    ll ans = 0;
    REP (r, n) {
        REP (l, r+1) {
            debug(l, r, qry(l, r), (pre[r] - pre[l]));
            ans = max(ans, qry(l, r) - (pre[r] - pre[l]));
        }
    }

    cout << ans << endl;
    return 0;
}


Measured memory_bytes: 199168