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
input = sys.stdin.readline

# from math import gcd as gcd, isqrt
# import bisect #-->For bisect.bisect_left=lower_bound and bisect_right=upper_bound

t = 1
# t = int(input())
for _ in range(t):
    n, q = map(int, input().split())
    a = sorted(list(map(int, input().split())))
    l = [0] * (n+1)
    for i in range(q):
        li, ri = map(int ,input().split())
        l[li-1] += 1
        l[ri] -= 1
    for i in range(1, n+1):
        l[i] += l[i-1]
    l.sort(reverse=True)
    ans = 0
    for i in range(n):
        ans += (a[i]*l[i])
    print(ans)