A = [0]*11
N = input()
for i in range(N):
	a,b,c = map(int,raw_input().split())
	A[a] += 1
	A[b] += 1
	A[c] += 1
ans = 0
for i in range(11):
	ans += A[i]/2
	A[i] %= 2
print ans + sum(A)/4