from collections import *

N = int(input())
A = list(map(int, input().split()))

ans = 0
pre = -1
cnt = 0
for a in A:
    if a == pre + 1:
        cnt += 1
    else:
        ans += cnt * (cnt - 1) // 2
        cnt = 1
    pre = a
    
ans += cnt * (cnt - 1) // 2
print(ans)