n=int(input())
a=list(map(int,input().split()))
b=[a[i+1]-a[i] for i in range(n-1)]
q=[]
for v in b:
	if len(q)==0 or q[-1][0]!=v:
		q+=[[v,0]]
	q[-1][1]+=1
g=0
for v,c in q:
	if v==1:
		g+=(c+1)*c//2
print(g)