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.
import heapq,math
from collections import defaultdict,deque
from os import getcwd, kill
from itertools import permutations


 
import sys, os.path
#sys.setrecursionlimit(10000000)
 
if(os.path.exists('C:/Users/Dhanush/Desktop/cp/input.txt')):
    sys.stdout = open('C:/Users/Dhanush/Desktop/cp/output.txt', 'w')
    sys.stdin = open('C:/Users/Dhanush/Desktop/cp/input.txt', 'r')
   
input=sys.stdin.readline


    
n,q=map(int,input().split())
l=list(map(int,input().split()))
freq=[0 for _ in range(n+1)]
queries=[]
for i in range(q):
    a,b=map(int,input().split())
    a-=1
    b-=1
    freq[a]+=1
    freq[b+1]-=1
    queries.append([a,b])
for i in range(1,n):
    freq[i]+=freq[i-1]
freq.sort(reverse=True)
l.sort(reverse=True)
ans=0
for i in range(n):
    ans+=freq[i]*l[i]
print(ans)
