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 N = 400 + 5;
int n, m;
long long a[N], ans = 1;
struct node {
  int s, f, c, r, id;
  bool operator<(const node& a) const { return id < a.id; }
} p[250000 + 5];
int judge(int s, int f, int c, int r, long long v) {
  long long now = v;
  while (s < f) {
    long long tmp = 1LL * (a[s + 1] - a[s]) * c;
    if (now < tmp) {
      now = v;
      r--;
    }
    if (now < tmp || r < 0)
      return 0;
    else {
      now -= tmp;
      s++;
    }
  }
  return 1;
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) scanf("%I64d", &a[i]);
  for (int i = 1, s, f, c, r; i <= m; i++) {
    scanf("%d%d%d%d", &p[i].s, &p[i].f, &p[i].c, &p[i].r);
    p[i].id = rand();
  }
  sort(p + 1, p + 1 + m);
  for (int i = 1; i <= m; i++) {
    int s = p[i].s, f = p[i].f, c = p[i].c, r = p[i].r;
    long long L = ans, R, Mid;
    while (!judge(s, f, c, r, L)) L *= 2;
    if (L == ans) continue;
    R = L, L /= 2;
    while (L <= R) {
      Mid = (L + R) / 2;
      if (judge(s, f, c, r, Mid)) {
        ans = Mid;
        R = Mid - 1;
      } else
        L = Mid + 1;
    }
  }
  printf("%I64d\n", ans);
  return 0;
}