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.
from bisect import bisect_right, bisect_left
from math import inf, gcd, sqrt, ceil, log2
from collections import defaultdict, Counter
from functools import cache, lru_cache
rvar = lambda: map(int, input().split())
rarr = lambda: list(map(int, input().split()))
rstr = lambda: input().split()
rint = lambda: int(input())

class BIT:
    def __init__(self, n):
        self.n = n
        self.T = [0] * (self.n + 1)


    def range_update(self, l, r, x = 1):
        self.update(l, x)
        self.update(r + 1, -x)

    def update(self, i, x):
        i += 1
        while i <= self.n:
            self.T[i] += x
            i += i & -i

    def pref(self, i):
        i += 1
        tot = 0
        while i > 0:
            tot += self.T[i]
            i -= i & -i
        return tot

        
'''Speed up'''
import sys
input = sys.stdin.readline

n, q = rvar()

arr = rarr()

bit = BIT(n)

for _ in range(q):
    l, r = rvar()
    l -= 1
    r -= 1
    bit.range_update(l, r)

freq = []
for i in range(n):
    freq.append(bit.pref(i))

freq.sort()
arr.sort()
res = 0

for i in range(n):
    res += arr[i] * freq[i]

print(res)



