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 M = 405;
const int N = 250005;
int read() {
  int x = 0, flag = 1;
  char c;
  while ((c = getchar()) < '0' || c > '9')
    if (c == '-') flag = -1;
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
  return x * flag;
}
int n, m, t[M], a[N], b[N], c[N], d[N], dp[2][M][M];
vector<int> v[M];
long long ans;
signed main() {
  n = read();
  m = read();
  for (int i = 1; i <= n; i++) t[i] = read();
  for (int i = 1; i <= m; i++) {
    a[i] = read();
    b[i] = read();
    c[i] = read();
    d[i] = read() + 1;
    d[i] = min(d[i], b[i] - a[i]);
    v[d[i]].push_back(i);
  }
  memset(dp, 0x3f, sizeof dp);
  for (int i = 1; i <= n; i++)
    for (int j = i; j <= n; j++) dp[1][i][j] = t[j] - t[i];
  for (int k = 1; k < n; k++) {
    for (int i = 0; i < v[k].size(); i++) {
      int x = v[k][i];
      ans = max(ans, 1ll * dp[k & 1][a[x]][b[x]] * c[x]);
    }
    for (int i = 1; i <= n; i++) dp[(k + 1) & 1][i][i] = 0;
    for (int i = 1; i <= n; i++) {
      int l = i;
      for (int j = i + 1; j <= n; j++) {
        while (dp[k & 1][i][l] < t[j] - t[l]) l++;
        dp[(k + 1) & 1][i][j] = min(dp[k & 1][i][l], t[j] - t[l - 1]);
      }
    }
  }
  printf("%lld\n", ans);
}