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 = input().split()
n = int(n)
q = int(q)
lst1 = list(map(int,input().split()))
count  =[0 for i in range(n)]
for i in range(q):
    lst2 = list(map(int,input().split()))
    l = lst2[0]
    m = lst2[1]
    count[l-1] +=1
    if m != n:
        count[m] -=1
    
for i in range(1,n):
    count[i]+=count[i-1]

# print(count)

count = list(sorted(count))
lst1 = list(sorted((lst1)))

ans = 0
for i in range(n):
    ans += count[i]*lst1[i]

print(ans)