import bisect
import itertools

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

D = dict()
for i in range(N):
    if A[i] not in D:
        D[A[i]] = [i]
    else:
        D[A[i]].append(i)

ans = 0
a1a3 = set()
for i1 in range(N-3):
    a1 = A[i1]
    a3 = a1+10
    if a3 not in D:
        continue
    for p in itertools.product([i1], D[a3]):
        a1a3.add(p)

a2a4 = set()
for i2 in range(1, N-2):
    a2 = A[i2]
    a4 = a2+1
    if a4 not in D:
        continue
    for p in itertools.product([i2], D[a4]):
        a2a4.add(p)

for a1, a3 in a1a3:
    for a2, a4 in a2a4:
        if a1<a2<a3<a4:
            ans+=1

print(ans)