#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC target( \
    "fma,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << '{';
  string sep;
  for (const auto &x : v) os << sep << x, sep = ", ";
  return os << '}';
}
template <typename T, size_t size>
ostream &operator<<(ostream &os, const array<T, size> &arr) {
  os << '{';
  string sep;
  for (const auto &x : arr) os << sep << x, sep = ", ";
  return os << '}';
}
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << ' ' << H;
  debug_out(T...);
}
class SegmentTree {
  struct Node {
    long long mx;
    long long lazy;
    Node() { mx = lazy = 0; }
  };
  const int LO, HI;
  vector<Node> seg;
  void push(int l, int r, int node) {
    if (seg[node].lazy == 0) return;
    seg[node].mx += seg[node].lazy;
    if (l != r) {
      seg[2 * node + 1].lazy += seg[node].lazy;
      seg[2 * node + 2].lazy += seg[node].lazy;
    }
    seg[node].lazy = 0;
  }
  void modify(int ql, int qr, long long delta, int l, int r, int node) {
    push(l, r, node);
    if (l > qr || r < ql) return;
    if (l >= ql && r <= qr) {
      seg[node].lazy = delta;
      push(l, r, node);
      return;
    }
    const int mid = l + (r - l) / 2;
    modify(ql, qr, delta, l, mid, 2 * node + 1);
    modify(ql, qr, delta, mid + 1, r, 2 * node + 2);
    seg[node].mx = max(seg[2 * node + 1].mx, seg[2 * node + 2].mx);
  }

 public:
  SegmentTree(int n) : LO(0), HI(n - 1) {
    seg.clear();
    seg.resize(4 * n);
  }
  void modify(int ql, int qr, long long delta) {
    modify(ql, qr, delta, LO, HI, 0);
  }
  long long best_way() { return seg[0].mx; }
};
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> arr(n + 1);
  for (int i = 1; i <= n; i++) cin >> arr[i];
  vector<vector<pair<int, int>>> g(n + 1);
  for (int i = 0; i < m; i++) {
    int st, et, w;
    cin >> st >> et >> w;
    g[et].emplace_back(st, w);
  }
  SegmentTree seg(n + 1);
  vector<long long> dp(n + 1);
  for (int i = 1; i <= n; i++) {
    for (auto to : g[i]) {
      const int st = to.first;
      const int w = to.second;
      seg.modify(0, st, w);
    }
    seg.modify(0, i, -arr[i]);
    dp[i] = max(dp[i - 1], seg.best_way());
    seg.modify(i + 1, i + 1, dp[i]);
  }
  cout << *max_element(dp.begin(), dp.end()) << '\n';
  return 0;
}
