a = []
b = 0
n = int(input())
c = n-1
for i in range(n):
    a.append(int(input()))
for i in range(n-1):
    while i < c:
        if (a[i] + a[c]) % 12 == 0:
            b += 1
        c -= 1
    с = n-1
print(b)