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.

if __name__=='__main__':
    nums = [int(i) for i in input().split(' ')]
    n = nums[0]
    q = nums[1]
    nums = [int(i) for i in input().split(' ')]
    
    nums = sorted(nums)
    
    indices = [0]*n
    
    while q:
        
        pos = [int(i) for i in input().split(' ')]
        l = pos[0]-1
        r = pos[1]-1
        
        for i in range(l, r+1):
            indices[i]+=1
        
        q-=1
        
    ret_ind = sorted(range(len(indices)), key=lambda index: indices[index])
    
    sum = 0
    
    for i in range(n):
        sum+=nums[i]*indices[ret_ind[i]]
    print(sum)