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 sys
# sys.setrecursionlimit(100000)
input=lambda:sys.stdin.readline().strip()
# write=lambda x:sys.stdout.write(str(x)+'\n')

# from decimal import Decimal
# from datetime import datetime,timedelta
# from random import randint
# from copy import deepcopy
# from collections import deque,Counter
# from heapq import heapify,heappush,heappop
# from bisect import bisect_left,bisect,insort
# from math import inf,sqrt,gcd,pow,ceil,floor,log,log2,log10,pi,sin,cos,tan,asin,acos,atan
# from functools import cmp_to_key,reduce
# from operator import or_,xor,add,mul
# from itertools import permutations,combinations,accumulate

def solve():
    n,q=map(int,input().split())
    a=list(map(int,input().split()))
    a.sort()
    b=[0]*n
    for i in range(q):
        l,r=map(int,input().split())
        l-=1;r-=1
        b[l]+=1
        if r+1<n:
            b[r+1]-=1
    for i in range(1,n):
        b[i]+=b[i-1]
    b.sort()
    res=0
    for i in range(n):
        res+=a[i]*b[i]
    print(res)
    return

# t=int(input())
# for _ in range(t):
#     solve()

solve()