#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> void Max(T &m, const T q) { if (m < q) m = q; }
template<typename T> void Min(T &m, const T q) { if (m > q) m = q; }
template<typename T1, typename T2> pair<T1, T2> operator+(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

int N, M;

vector<lint> As;

int main()
{
    cin >> N >> M;
    As.resize(N + 1);
    REP(i, N - 1)
    {
        lint tmp;
        cin >> tmp;
        As[i + 2] = As[i + 1] + tmp;
    }

    vector<vector<lint>> s, B;
    ndarray(s, N + 2, N + 2);
    ndarray(B, M, N + 1);

    REP(n, N) REP(m, M) cin >> B[m][n + 1];

    REP(m, M)
    {
        set<int> used;
        used.insert(0);
        used.insert(N + 1);
        priority_queue<pint, vector<pint>> pq;
        FOR(i, 1, N + 1) pq.push(pint(B[m][i], i));
        while (!pq.empty())
        {
            pint pa = pq.top();
            pq.pop();

            int n = pa.second;
            int r = *used.lower_bound(n);
            int l = *prev(used.lower_bound(n)) + 1;

            s[l][n] += pa.first;
            s[l][r] -= pa.first;
            s[n + 1][n] -= pa.first;
            s[n + 1][r] += pa.first;
            used.insert(n);
        }
    }

    REP(i, N + 1) REP(j, N + 1) s[i][j + 1] += s[i][j];
    REP(i, N + 1) REP(j, N + 1) s[i + 1][j] += s[i][j];

    lint ans = 0;
    FOR(i, 1, N + 1) FOR(j, i, N + 1) Max(ans, s[i][j] - (As[j] - As[i]));

    cout << ans << endl;
}

Measured memory_bytes: 204148