use std::io::{self, Stdin};
use std::str::{self, FromStr};
use std::error::Error;
use std::thread;
use std::collections::*;

fn exec() {
    let mut sc = Scanner::new();
    let n: usize = sc.ne();
    let mut edge = vec![(0, 0); n];
    let mut num = BTreeMap::new();
    for i in 0..n {
        let y1 = sc.ne::<usize>() - 1;
        let x1 = sc.ne::<usize>() - 1;
        let y2 = sc.ne::<usize>() - 1;
        let x2 = sc.ne::<usize>() - 1;
        let n1 = y1 * 100 + x1;
        let n2 = y2 * 100 + x2;
        edge[i] = (n1, n2);
        num.insert(n1, 0);
        num.insert(n2, 0);
    }
    let m = num.len();
    let mut t = 0;
    for (_, val) in num.iter_mut() {
        *val = t;
        t += 1;
    }
    let mut adj = vec![Vec::new(); n + m];
    for i in 0..n {
        let u = num[&edge[i].0];
        let v = num[&edge[i].1];
        adj[i].push(n + u);
        adj[i].push(n + v);
        adj[n + u].push(i);
        adj[n + v].push(i);
    }
    let ans = match bimatch(&adj, n) {
        val if val == n => "YES",
        _ => "NO",
    };
    println!("{}", ans);
}
fn bimatch(adj: &Vec<Vec<usize>>, ln: usize) -> usize {
    fn dfs(cur: usize,
           adj: &Vec<Vec<usize>>,
           mut match_to: &mut Vec<Option<usize>>,
           mut used: &mut Vec<bool>)
           -> bool {
        for &nxt in &adj[cur] {
            if used[nxt] {
                continue;
            }
            used[nxt] = true;
            let assign = match match_to[nxt] {
                Some(v) => dfs(v, &adj, &mut match_to, &mut used),
                None => true,
            };
            if assign {
                match_to[cur] = Some(nxt);
                match_to[nxt] = Some(cur);
                return true;
            }
        }
        false
    }
    let n = adj.len();
    let mut match_to: Vec<Option<usize>> = vec![None; n];
    let mut res = 0;
    for i in 0..ln {
        if match_to[i] != None {
            continue;
        }
        let mut used = vec![false; n];
        if dfs(i, &adj, &mut match_to, &mut used) {
            res += 1;
        }
    }
    res
}


fn main() {
    const DEFAULT_STACK: usize = 16 * 1024 * 1024;
    let builder = thread::Builder::new();
    let th = builder.stack_size(DEFAULT_STACK);
    let handle = th.spawn(|| { exec(); }).unwrap();
    let _ = handle.join();
}

#[allow(dead_code)]
struct Scanner {
    stdin: Stdin,
    id: usize,
    buf: Vec<u8>,
}

#[allow(dead_code)]
impl Scanner {
    fn new() -> Scanner {
        Scanner {
            stdin: io::stdin(),
            id: 0,
            buf: Vec::new(),
        }
    }
    fn next_line(&mut self) -> Option<String> {
        let mut res = String::new();
        match self.stdin.read_line(&mut res) {
            Ok(0) => return None,
            Ok(_) => Some(res),
            Err(why) => panic!("error in read_line: {}", why.description()),
        }
    }
    fn next<T: FromStr>(&mut self) -> Option<T> {
        while self.buf.len() == 0 {
            self.buf = match self.next_line() {
                Some(r) => {
                    self.id = 0;
                    r.trim().as_bytes().to_owned()
                }
                None => return None,
            };
        }
        let l = self.id;
        assert!(self.buf[l] != b' ');
        let n = self.buf.len();
        let mut r = l;
        while r < n && self.buf[r] != b' ' {
            r += 1;
        }
        let res = match str::from_utf8(&self.buf[l..r]).ok().unwrap().parse::<T>() {
            Ok(s) => Some(s),
            Err(_) => panic!("parse error"),
        };
        while r < n && self.buf[r] == b' ' {
            r += 1;
        }
        if r == n {
            self.buf.clear();
        } else {
            self.id = r;
        }
        res
    }
    fn ne<T: FromStr>(&mut self) -> T {
        self.next::<T>().unwrap()
    }
}