Let's denote a function 

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You are given an array a consisting of n integers. You have to calculate the sum of d(ai, aj) over all pairs (i, j) such that 1 ≤ i ≤ j ≤ n.

Input

The first line contains one integer n (1 ≤ n ≤ 200000) — the number of elements in a.

The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 109) — elements of the array. 

Output

Print one integer — the sum of d(ai, aj) over all pairs (i, j) such that 1 ≤ i ≤ j ≤ n.

Examples

Input

5
1 2 3 1 3


Output

4


Input

4
6 6 5 5


Output

0


Input

4
6 6 4 4


Output

-8

Note

In the first example:

  1. d(a1, a2) = 0; 
  2. d(a1, a3) = 2; 
  3. d(a1, a4) = 0; 
  4. d(a1, a5) = 2; 
  5. d(a2, a3) = 0; 
  6. d(a2, a4) = 0; 
  7. d(a2, a5) = 0; 
  8. d(a3, a4) = - 2; 
  9. d(a3, a5) = 0; 
  10. d(a4, a5) = 2. 
def update(fenwick, idx, val, n):
    while idx<n:
        fenwick[idx]+=val
        idx+=(idx & (-idx))

def get_sum(fenwick, idx):
    sum=0
    while idx>0:
        sum+=fenwick[idx]
        idx-=(idx & (-idx))
    return sum

def count_smaller_elements(arr):
    temp=arr.copy()
    temp.sort()
    curr_size=1
    Hashed_Value={}
    ## Hashing values so that we can implement fenwick of size N instead of size Max Value
    for item in temp:
        if item not in Hashed_Value:
            Hashed_Value[item]=curr_size
            curr_size+=1
    
    fenwick=[0]*(curr_size)
    
    for i in range(n):
        temp[i]=Hashed_Value[arr[i]]
    temp=temp[::-1]
    count_smaller=[0]*n
    
    for i in range(n):
        count_smaller[i]=get_sum(fenwick, temp[i]-1)
        update(fenwick, temp[i] , 1 ,curr_size)
    return count_smaller[::-1]



n=int(input())
l1=list(map(int,input().split()))
d1={}
ans=0
for i in range(-1,-n-1,-1):
    if l1[i] not in d1:
        ans-=l1[i]*(abs(i)-1)
    else :
        ans-=(l1[i])*(abs(i)-1-d1[l1[i]])
    if l1[i] not in d1:
        d1[l1[i]]=1
    else :
        d1[l1[i]]+=1
d1={}

for i in range(n):
    if l1[i] not in d1:
        ans+=l1[i]*i
    else :
        ans+=l1[i]*(i-d1[l1[i]])
    if l1[i] not in d1:
        d1[l1[i]]=1
    else :
        d1[l1[i]]+=1

for item in l1:
    if item-1 in d1:
        ans-=d1[item-1]
    if item+1 in d1:
        ans+=d1[item+1]
    if item not in d1:
        d1[item]=1
    else :
        d1[item]+=1
print(ans)