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
from functools import reduce
input = sys.stdin.readline
import time

############ ---- Input Functions ---- ############
def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))

n, nr = inlt()
seq = inlt()
# print("firstsorting... ")
sseq = sorted(seq,reverse=True)
# print("firstsorted.")
qs = []
for i in range(0,nr):
    qs.append(inlt())
heat = [0]*n
begins = [0]*n
ends = [0]*n
# print("beginending...")
for q in qs:
    begins[q[0]-1]+=1
    ends[q[1]-1]+=1
# print("beginended.")

# print("pre-heating... ")
for i in range(1,len(begins)):
    begins[i] += begins[i-1]
    ends[i] += ends[i-1]
# print("pre-heated.")
# print(begins)
# print(ends)

# print("heating...")
# for q in qs:
#     for i in range(q[0]-1,q[1]):
#         heat[i] += 1
# print(heat)
for i in range(len(heat)):
    heat[i] = begins[i]-(ends[i-1] if i-1>0 else 0)
# print(heat)
# print("heated.")

# print("secondsorting... ")
sheat = sorted(heat,reverse=True)
# print("secondsorted.")
# print(sseq, sheat)
print(reduce(lambda x,y: x+y, map(lambda t: t[0]*t[1], zip(sseq,sheat))))
# print("reduced")