fn inside(a: &mut [usize; 3], b: &mut [usize; 3]) -> bool {
    let mut ok = true;
    for i in 0..3 {
        if a[i] == std::usize::MAX { continue; }
        ok = false;
        for j in 0..3 {
            if b[j] == std::usize::MAX { continue; }
            if a[i] < b[j] {
                let tmp = (a[i], b[j]);
                a[i] = std::usize::MAX;
                b[j] = std::usize::MAX;
                let res = inside(a, b);
                a[i] = tmp.0;
                b[j] = tmp.1;
                if res { return true; }
            }
        }
    }
    ok
}

fn main() {
    let mut scanner = Scanner::new();
    let n = scanner.next_usize();
    let mut g = vec![Vec::new(); n];

    let mut t = Vec::new();
    for i in 0..n {
        t.push([scanner.next_usize(), scanner.next_usize(), scanner.next_usize()]);
        for j in 0..i {
            let mut a = t[j];
            let mut b = t[i];
            if inside(&mut a, &mut b) { g[i].push(j) }
            if inside(&mut b, &mut a) { g[j].push(i) }
        }
    }

    let mut dp = vec![1; n];
    for _ in 0..n {
        for i in 0..n {
            for j in 0..g[i].len() {
                dp[i] = std::cmp::max(dp[i], dp[g[i][j]] + 1)
            }
        }
    }

    println!("{}", dp.iter().max().unwrap());
}


struct Scanner {
    reader: std::io::Stdin,
    tokens: std::collections::VecDeque<String>,
}

impl Scanner {
    fn new() -> Self {
        Scanner {
            reader: std::io::stdin(),
            tokens: std::collections::VecDeque::new(),
        }
    }

    fn next(&mut self) -> String {
        if self.tokens.is_empty() {
        let mut s = String::new();
            loop {
                self.reader.read_line(&mut s).ok();
                let s = s.trim();
                if s.len() != 0 {
                    for it in s.split_whitespace() {
                        self.tokens.push_back(it.into())
                    }
                    break;
                }
            }
        }
        self.tokens.pop_front().unwrap()
    }

    fn next_generics<T>(&mut self) -> T where
        T: std::str::FromStr + std::marker::Copy,
        <T as std::str::FromStr>::Err: std::fmt::Debug
    {
        self.next().parse().unwrap()
    }
    
    #[allow(dead_code)] fn next_i32(&mut self) -> i32 { self.next_generics::<i32>() }
    #[allow(dead_code)] fn next_i64(&mut self) -> i64 { self.next_generics::<i64>() }
    #[allow(dead_code)] fn next_u64(&mut self) -> u64 { self.next_generics::<u64>() }
    #[allow(dead_code)] fn next_usize(&mut self) -> usize { self.next_generics::<usize>() }
}