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 JAVA):

Solution:
/*
    Idea from Blogewoosh #6
 */

//created by Whiplash99
import java.io.*;
import java.util.*;
public class F
{
    private static final long max=Long.MAX_VALUE;
    private static int[] a,s,f,r,order;
    private static long[] c;

    private static void shuffleArray(int[] arr)
    {
        int n = arr.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i)
        {
            int tmp = arr[i];
            int randomPos = i + rnd.nextInt(n-i);
            arr[i] = arr[randomPos];
            arr[randomPos] = tmp;
        }
    }
    private static boolean check(int id, long V)
    {
        long used=0; int count=r[id];
        for(int i=s[id]+1;i<=f[id];i++)
        {
            long cur=c[id]*(a[i]-a[i-1]);
            used+=cur;

            if(used>V)
            {
                if(count==0) return false;
                count--; used=cur;
                if(used>V) return false;
            }
        }
        return true;
    }
    private static long bSearch(int id, long cur)
    {
        long l=cur,r=max,mid;
        while (l<=r)
        {
            mid=l+(r-l)/2;
            if(check(id,mid))
            {
                cur=mid;
                r=mid-1;
            }
            else l=mid+1;
        }
        return cur;
    }
    public static void main(String[] args) throws IOException
    {
        Reader reader=new Reader();
        int i,N; long ans=0;

        N=reader.nextInt();
        int M=reader.nextInt();

        a=new int[N]; s=new int[M]; f=new int[M];
        c=new long[M]; r=new int[M]; order=new int[M];

        for(i=0;i<N;i++) a[i]=reader.nextInt();
        for(i=0;i<M;i++)
        {
            s[i]=reader.nextInt()-1;
            f[i]=reader.nextInt()-1;
            c[i]=reader.nextInt();
            r[i]=reader.nextInt();

            order[i]=i;
        }

        shuffleArray(order);
        for(i=0;i<M;i++)
        {
            if(check(order[i],ans)) continue;
            ans=bSearch(order[i],ans+1);
        }
        System.out.println(ans);
    }
    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;private DataInputStream din;private byte[] buffer;private int bufferPointer, bytesRead;
        public Reader(){din=new DataInputStream(System.in);buffer=new byte[BUFFER_SIZE];bufferPointer=bytesRead=0;
        }public Reader(String file_name) throws IOException{din=new DataInputStream(new FileInputStream(file_name));buffer=new byte[BUFFER_SIZE];bufferPointer=bytesRead=0;
        }public String readLine() throws IOException{byte[] buf=new byte[64];int cnt=0,c;while((c=read())!=-1){if(c=='\n')break;buf[cnt++]=(byte)c;}return new String(buf,0,cnt);
        }public int nextInt() throws IOException{int ret=0;byte c=read();while(c<=' ')c=read();boolean neg=(c=='-');if(neg)c=read();do{ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');if(neg)return -ret;return ret;
        }public long nextLong() throws IOException{long ret=0;byte c=read();while(c<=' ')c=read();boolean neg=(c=='-');if(neg)c=read();do{ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');if(neg)return -ret;return ret;
        }public double nextDouble() throws IOException{double ret=0,div=1;byte c=read();while(c<=' ')c=read();boolean neg=(c=='-');if(neg)c = read();do {ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');if(c=='.')while((c=read())>='0'&&c<='9')ret+=(c-'0')/(div*=10);if(neg)return -ret;return ret;
        }private void fillBuffer() throws IOException{bytesRead=din.read(buffer,bufferPointer=0,BUFFER_SIZE);if(bytesRead==-1)buffer[0]=-1;
        }private byte read() throws IOException{if(bufferPointer==bytesRead)fillBuffer();return buffer[bufferPointer++];
        }public void close() throws IOException{if(din==null) return;din.close();}
    }
}