n = gets.chomp.to_i

items = {}
n.times {
    a, b, c = gets.chomp.split.map &:to_i
    items[a] ||= 0
    items[b] ||= 0
    items[c] ||= 0
    items[a] += 1
    items[b] += 1
    items[c] += 1
}

power_up = 0
remain = 0
items.each {|_, value|
    power_up += value / 2
    remain += value % 2
}

p power_up + remain / 4