from collections import defaultdict

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