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 pf(n):
#	if(n > 1):
#		tst=0
#		for k in range(2, int((n)**(0.5)) + 1):
#			if (n % k == 0):
#				tst = 1
#				break
#		if (tst == 0):
#			return 1
#		else:
#			return 0
#	return 0
# import io,os
# input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline
# from sys import stdin
# input = lambda: stdin.buffer.readline().rstrip(b'\r\n').decode('ascii')
# from queue import PriorityQueue as pq
# from  heapq import heappop,heappush
# from math import gcd,lcm
from collections import defaultdict as mmap
tt=1
# tt=int(input())
for _ in range(tt):
	# n=int(input())
	n, q = map(int, input().split())
	a = list(map(int, input().split()))
	a.sort()
	v = [0] * n
	for i in range(q):
		l, r = map(int, input().split())
		v[l - 1] += 1 
		if(r < n):
			v[r] -= 1
	for i in range(1, n):
		v[i] += v[i - 1]
	v.sort()
	s = 0 
	for i in range(n):
		s += a[i] * v[i]
	print(s)
 				 				     	 		     	 	   	