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;
struct tir {
  long long int s, f, c, r;
};
const int N = 500;
vector<long long int> a(N, 0);
int n;
long long ans = 1;
bool sprawdz(tir z, long long v) {
  long long int s, f, c, r;
  s = z.s;
  f = z.f;
  c = z.c;
  r = z.r;
  s--;
  f--;
  long long akt = v;
  for (int i = s; i < f; i++) {
    long long t = a[i + 1] - a[i];
    if (akt < t * c) {
      r--;
      akt = v;
      if (r < 0) return false;
      if (akt < t * c) return false;
    }
    akt -= t * c;
  }
  return true;
}
void update(tir s) {
  bool ok = sprawdz(s, ans);
  if (ok) return;
  long long lo, hi;
  lo = ans;
  hi = 1e18;
  while (lo + 2 < hi) {
    long long mid = (lo + hi) / 2;
    if (sprawdz(s, mid) == true)
      hi = mid;
    else
      lo = mid + 1;
  }
  while (sprawdz(s, hi) == true) hi--;
  hi++;
  ans = max(ans, hi);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) cin >> a[i];
  tir* s = new tir[m];
  for (int i = 0; i < m; i++) {
    cin >> s[i].s >> s[i].f >> s[i].c >> s[i].r;
  }
  srand(2134123);
  random_shuffle(s, s + m);
  for (int i = 0; i < m; i++) {
    update(s[i]);
  }
  cout << ans;
  return 0;
}