class Problem0029:
	def solve(this):
		n = int(input())
		res = {}
		for i in range(n):
			a,b,c = map(int, input().split())
			res[a] = res.get(a, 0) + 1
			res[b] = res.get(b, 0) + 1
			res[c] = res.get(c, 0) + 1
	
		cnt = 0
		remain = 0
		for v in res.values():
			cnt += v // 2
			remain += v % 2
		cnt += remain // 5
		print(cnt)

if __name__ == "__main__":
	problem = Problem0029()
	problem.solve()