from collections import Counter
import sys 

input = sys.stdin.readline
# sys.setrecursionlimit(25000)

n = int(input())
abcn = []
for i in range(n):
    abcn += list(map(int, input().split(' ')))

c = Counter(abcn)

count = 0
m = 0
for i in c.keys():
    count += c[i] // 2
    m += c[i] % 2

print(count + m // 4)