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

M = 2005        
ans = 0
for i in range(N):
    D = [0] * M
    for j in range(i + 1, N):
        if A[j] >= A[i] + 2:
            D[A[j]] += 1
    now = 0
    for j in range(i - 1, -1, -1):
        if A[j] == A[i] - 10:
            ans += now
        now += D[A[j] + 1]
        
print(ans)