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 solve(arr, qs):
    ac = [0] * (len(arr) + 1)
    for l, r in qs:
        ac[l-1] += 1
        ac[r] -= 1

    for i in range(1, len(ac)):
        ac[i] += ac[i-1]
    ac.pop()
    ac.sort()
    arr.sort()
    return sum(a*q for a, q in zip(arr, ac))


def main():
    n, q = map(int, input().split())
    arr = list(map(int, input().split()))
    qs = []
    for _ in range(q):
        l, r = map(int, input().split())
        qs.append((l, r))

    print(solve(arr, qs))


if __name__ == '__main__':
    main()