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 =list(map(int,input().split()))
nums= list(map(int,input().split()))
queries = []
for _ in range(q):
    questions = list(map(int,input().split()))
    queries.append(questions)

q_pre= [1]*(n+1)

for query in queries:
    q_pre[query[0]-1]+=1
    q_pre[query[1]]-=1

prefix_sm = [0]*(n+1)

for idx,q in enumerate(q_pre[0:len(q_pre)-1],start=1):
    prefix_sm[idx] = prefix_sm[idx-1] + q


prefix_sm[1]-=1
index_prefix = []
for idx in range(1,len(prefix_sm)):
    prev = prefix_sm[idx-1]
    curr = prefix_sm[idx]
    index_p = curr - prev
    
    pair = (idx, index_p)
    index_prefix.append(pair)

index_prefix.sort(key=lambda x:x[1],reverse=True)
new_list = []

for pairs in index_prefix:
    new_list.append(nums[pairs[0]-1])

prefix_sum = [0]*(n+1)
for i in range(1,n+1):
    prefix_sum[i] = prefix_sum[i-1] + new_list[i-1]
total=0
for query in queries:
    summation = prefix_sum[query[1]] - prefix_sum[query[0]-1]
    total+=summation
    
print(total)
    
    
    
    
    
                
            



    
