N = int(raw_input());

count = [0] * 11

for i in range(0,N):
    A,B,C = map(int, raw_input().split())
    count[A] += 1
    count[B] += 1
    count[C] += 1

ans = 0
tmp = 0
for j in count:
    ans += j/2
    tmp += j%2

print ans + tmp/4