Problem: There are n cities along the road, which can be represented as a straight line. The i-th city is situated at the distance of a_i kilometers from the origin. All cities are situated in the same direction from the origin. There are m trucks travelling from one city to another. 

Each truck can be described by 4 integers: starting city s_i, finishing city f_i, fuel consumption c_i and number of possible refuelings r_i. The i-th truck will spend c_i litres of fuel per one kilometer. 

When a truck arrives in some city, it can be refueled (but refueling is impossible in the middle of nowhere). The i-th truck can be refueled at most r_i times. Each refueling makes truck's gas-tank full. All trucks start with full gas-tank.

All trucks will have gas-tanks of the same size V litres. You should find minimum possible V such that all trucks can reach their destinations without refueling more times than allowed.

Input

First line contains two integers n and m (2 ≤ n ≤ 400, 1 ≤ m ≤ 250000) — the number of cities and trucks.

The second line contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^9, a_i < a_{i+1}) — positions of cities in the ascending order.

Next m lines contains 4 integers each. The i-th line contains integers s_i, f_i, c_i, r_i (1 ≤ s_i < f_i ≤ n, 1 ≤ c_i ≤ 10^9, 0 ≤ r_i ≤ n) — the description of the i-th truck.

Output

Print the only integer — minimum possible size of gas-tanks V such that all trucks can reach their destinations.

Example

Input


7 6
2 5 7 10 14 15 17
1 3 10 0
1 7 12 7
4 5 13 3
4 7 10 1
4 7 10 1
1 5 11 2


Output


55

Note

Let's look at queries in details: 

  1. the 1-st truck must arrive at position 7 from 2 without refuelling, so it needs gas-tank of volume at least 50. 
  2. the 2-nd truck must arrive at position 17 from 2 and can be refueled at any city (if it is on the path between starting point and ending point), so it needs gas-tank of volume at least 48. 
  3. the 3-rd truck must arrive at position 14 from 10, there is no city between, so it needs gas-tank of volume at least 52. 
  4. the 4-th truck must arrive at position 17 from 10 and can be refueled only one time: it's optimal to refuel at 5-th city (position 14) so it needs gas-tank of volume at least 40. 
  5. the 5-th truck has the same description, so it also needs gas-tank of volume at least 40. 
  6. the 6-th truck must arrive at position 14 from 2 and can be refueled two times: first time in city 2 or 3 and second time in city 4 so it needs gas-tank of volume at least 55. 

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int maxn = 410;
const int maxm = 251000;
const int oo = 1e9;
int n, m;
int st[maxm], ed[maxm], c[maxm], rr[maxm];
int dis[maxn];
int dp[maxn][maxn];
long long ans = 0;
vector<int> quest[maxn];
int que[maxn], s, t;
int main() {
  std::ios::sync_with_stdio(false);
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> dis[i];
  for (int i = 1; i <= m; i++) {
    cin >> st[i] >> ed[i] >> c[i] >> rr[i];
    quest[st[i]].push_back(i);
  }
  for (int l = 1; l <= n; l++) {
    for (int r = l; r <= n; r++) dp[1][r] = dis[r] - dis[l];
    s = 1, t = 0;
    for (int k = 2; k <= n + 1; k++) {
      dp[k][l] = 0;
      que[1] = l;
      s = t = 1;
      for (int r = l + 1; r <= n; r++) {
        t++;
        que[t] = r;
        dp[k][r] = oo;
        while (s <= t) {
          dp[k][r] =
              min(dp[k][r], max(dp[k - 1][que[s]], dis[r] - dis[que[s]]));
          if (dp[k - 1][que[s]] < dis[r] - dis[que[s]])
            s++;
          else
            break;
        }
      }
    }
    for (int i = 0; i < quest[l].size(); i++) {
      int now = quest[l][i];
      ans = max(ans, 1ll * dp[rr[now] + 1][ed[now]] * c[now]);
    }
  }
  cout << ans << endl;
  return 0;
}