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
import os
from collections import Counter


# Read from file.
if len(sys.argv) > 1:
    if os.path.exists((file_name := sys.argv[1])):
        with open(file_name, 'r') as f:
            input = iter(f.readlines()).__next__


n, q = map(int, input().split())
a = map(int, input().split())
# idx_counts = [0] * n
ranges = list()
for _ in range(q):
    l, r = map(int, input().split())
    ranges.extend(list(range(l-1, r)))
    # for idx in range(l-1, r):
    #     idx_counts[idx] += 1

c = Counter(ranges)

# print(ranges)
# print(c)
ans = sum([ai*bi for ai, bi in zip(sorted(a), sorted(c.values()))])
print(ans)
