The little girl loves the problems on array queries very much.

One day she came across a rather well-known problem: you've got an array of $n$ elements (the elements of the array are indexed starting from 1); also, there are $q$ queries, each one is defined by a pair of integers $l_i$, $r_i$ $(1 \le l_i \le r_i \le n)$. You need to find for each query the sum of elements of the array with indexes from $l_i$ to $r_i$, inclusive.

The little girl found the problem rather boring. She decided to reorder the array elements before replying to the queries in a way that makes the sum of query replies maximum possible. Your task is to find the value of this maximum sum.
The first line contains two space-separated integers $n$ ($1 \le n \le 2\cdot10^5$) and $q$ ($1 \le q \le 2\cdot10^5$) — the number of elements in the array and the number of queries, correspondingly.

The next line contains $n$ space-separated integers $a_i$ ($1 \le a_i \le 2\cdot10^5$) — the array elements.

Each of the following $q$ lines contains two space-separated integers $l_i$ and $r_i$ ($1 \le l_i \le r_i \le n$) — the $i$-th query.
def little():
  n,q = input().split()
  n = int(n)
  q = int(q)
  arr = [0] * (n)
  arr = list(map(int, input().split(' ')[:n]))
  arr2 = [0] * (n + 1)
  
  l = 0
  r = 0
  i = 0
  q = int(q)
  
  while (i < q):
    l, r = input().split()
    l = int(l)
    r = int(r)
    arr2[l] += 1
    if (r < n):
      arr2[r + 1] += -1
    i += 1
    
  i = 1
  while (i <= n):
    arr2[i] += arr2[i - 1]
    i += 1
      
  arr.sort()
  arr2.sort()
    
  sum= 0
  i = 0
    
  while (i < n):
    sum+= arr[i] * arr2[i + 1]
    i += 1
  print(sum)
  
little()