use proconio::input;

fn main() {
	input! {
		n: usize,
		a: [[usize; 3]; n],
	}

    let mut ans = 0;

    let mut arr  = vec![0; 11];

    for v in a {
        for n in v {
            arr[n] += 1;
        }
    }

    let mut remain = 0;

    for i in 1..arr.len() {
        ans += arr[i] / 2;
        remain += arr[i] % 2;
    }

    println!("{}", ans + remain / 4);
}