weapon = [0] * 11
N = int(input())
for _ in range(N):
    i, j, k = map(int, input().split())
    weapon[i] += 1
    weapon[j] += 1
    weapon[k] += 1

lvup = 0
tmp = 0
for w in weapon:
    if w >= 2:
        lvup += (w // 2)
        tmp += (w % 2)
    elif w >= 1:
        tmp += 1

lvup += (tmp // 4)

print(lvup)