from collections import deque
n=int(input())
a=list(map(int,input().split()))
q=deque()
ans=0
for i in a:
    if len(q)==0:
        q.append(i)
        continue
    if q[-1]+1==i:
        q.append(i)
    else:
        ans+=len(q)*(len(q)-1)//2
        while q:
            q.popleft()
ans+=len(q)*(len(q)-1)//2
print(ans)