from itertools import combinations

team = {}
result = 0


def valid(t):
    for i in range(2, 10 + 1):
        if t[0] % i == t[1] % i:
            return False

    return True


n = int(input())

for i in range(n):
    team[i] = int(input())

g = combinations(team.values(), r=2)
for i in g:
    if valid(i):
        result += 1

print(result)