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.
n, q = map(int, input().split())

a = list(map(int, input().split()))

height_map = [0] * n
for _ in range(q):
    l, r = map(int, input().split())
    for i in range(l - 1, r):
        height_map[i] += 1

height_map_sorted = sorted(height_map)
a_sorted = sorted(a)

out = 0
for i in range(n):
    i_ = height_map_sorted.index(height_map[i])
    out += a_sorted[i_] * height_map_sorted[i_]

    del a_sorted[i_]
    del height_map_sorted[i_]

print(out)
