n = io.read("*n")
t = {}
cnt = 0
for i = 1, n * 3 do
    a = io.read("*n")
    if(t[a] == nil) then t[a] = true else t[a], cnt = nil, cnt + 1 end
end
subcnt = 0
for k, v in pairs(t) do
    if(subcnt == 3) then subcnt, cnt = 0, cnt + 1 else subcnt = subcnt + 1 end
end
print(cnt)