use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn get_line() -> String {
    let stdin = stdin();
    let mut line = String::new();
    stdin.lock().read_line(&mut line).expect("io error.");
    line.trim().to_string()
}

#[allow(dead_code)]
fn get_word<T: FromStr>() -> T {
    (&get_line()).parse().ok().expect("parse error.")
}

#[allow(dead_code)]
fn get_vec<T: FromStr>() -> Vec<T> {
    (&get_line()).split(' ').map(|x| x.parse().ok().expect("parse error.")).collect()
}

fn main() {
    let n = get_word::<u8>();

    let mut items: Vec<u8> = vec![0; 20];
    let mut ans: u8 = 0;

    for _ in 0..n {
        let v = get_vec::<usize>();
        for i in 0..3 {
            ans += items[v[i]];
            items[v[i]] = 1 - items[v[i]];
        }
    }

    // println!("{:?}", items);

    ans += items[0..20].iter().sum::<u8>() / 4;
    println!("{}", ans);
}