n = gets.to_i
array = Array.new(10, 0)
n.times do
    a, b, c = gets.split().map(&:to_i)
    array[a-1] += 1
    array[b-1] += 1
    array[c-1] += 1
end
ans = 0
plus = 0
for i in 0..9 do
    ans += array[i]/2
    plus += array[i] % 2
end

p ans+plus/4