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 = 405;
const int maxm = 250005;
int n, m, a[maxn];
long long dp[2][maxn][maxn];
struct Car {
  int r, s, f, c;
  void read() { scanf("%d%d%d%d", &s, &f, &c, &r); }
  bool operator<(const Car& x) const {
    if (r != x.r) return r < x.r;
    if (s != x.s) return s < x.s;
    if (f != x.f) return f < x.f;
    return c < x.c;
  }
  bool operator==(const Car& x) const {
    return r == x.r && s == x.s && f == x.f;
  }
} car[maxm];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; i++) {
    scanf("%d", a + i);
  }
  for (int i = 1; i <= m; i++) {
    car[i].read();
    car[i].r++;
  }
  sort(car + 1, car + 1 + m);
  for (int i = 1; i <= n; i++) {
    for (int j = i; j <= n; j++) {
      dp[1][i][j] = a[j] - a[i];
    }
  }
  int pl = 1;
  long long ans = 0;
  for (int r = 1; r <= n + 1; r++) {
    for (int i = 1; i <= n; i++) {
      int k = i;
      for (int j = i + 1; j <= n; j++) {
        Car cur = (Car){r, i, j, 0};
        for (; pl <= m && (car[pl] < cur || car[pl] == cur); pl++) {
          if (car[pl] < cur) continue;
          ans = max(ans, dp[r & 1][i][j] * car[pl].c);
        }
        for (; k < j && dp[r & 1][i][k] <= a[j] - a[k]; k++)
          ;
        k--;
        if (a[j] - a[k] <= dp[r & 1][i][k + 1]) {
          dp[~r & 1][i][j] = a[j] - a[k];
        } else {
          k++;
          dp[~r & 1][i][j] = dp[r & 1][i][k];
        }
      }
    }
  }
  printf("%I64d\n", ans);
  return 0;
}