Edited by author 12.03.2016 20:21

n = int(input())
a = []
summ = 0
for i in range(n):
    a.append(int(input()))
b = list(set(a))
for i in range(len(b)):
    c=a.count(b[i])
    if c > 3:
        summ+=c//4
print(summ)