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 math
# Fast input
input = sys.stdin.readline
# Fast output
def print(*args, **kwargs):
    sep = kwargs.get('sep', ' ')
    end = kwargs.get('end', '\n')
    file = kwargs.get('file', sys.stdout)
    flush = kwargs.get('flush', False)
    output = sep.join(map(str, args)) + end
    file.write(output)
    if flush:
        file.flush()

def listin():
   
    l=list(map(int,input().split()))
    return l
def two():
    n,m=map(int,input().split())
    return n,m
def three():
    n,m,p=map(int,input().split())
    return n,m,p

n,m=two()
l=listin()
x=[0]*(n+1)
for i in range(m):
    p,q=two()
    x[p-1]+=1
    x[q]-=1
for i in range(n):
    x[i+1]+=x[i]
x.pop()
l.sort()
x.sort()
s=0
for i in range(n):
    s+=x[i]*l[i]
print(s)