n = int(input())
a = list(map(int, input().split(' ')))
m = max(a)
ans = 0
for i in range(n):
    buf = [0] * (m+2)
    for j in range(i, n):
        buf[a[j]] += 1
    for j in range(i, n):
        if a[j] == a[i] + 10:
            for k in range(i+1, j):
                estimate = a[k] - a[i] - 10
                if estimate > 0 and buf[a[k] + 1] > 0:
                    ans += buf[a[k]+1]
        buf[a[j]] -= 1
print(ans)