#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get { 
    ([$t: ty]) => { 
        { 
            let mut line = String::new(); 
            stdin().read_line(&mut line).unwrap(); 
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    // ($t: ty, [$x: ty]) => {
    //     { 
    //         let mut line = String::new();
    //         stdin().read_line(&mut line).unwrap();
    //         let mut iter = line.split_whitespace();
    //         (iter.next().unwrap().parse::<$t>().unwrap(), get!([$x]))
    //     }
    // };
    // ($t: ty, [$x: ty];$n: expr) => {
    //     (0..$n).map(|_|get!($t, [$x])).collect::<Vec<_>>()
    // };
    ($($t: ty),*) => {
        { 
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

fn solve() {
    let (n,m) = get!(usize, usize);
    let kl = get!([usize]; n);

    let mut nodes = vec![Vec::new(); n+m+2];
    for i in 0..n {
        for &l in kl[i].iter().skip(1) {
            nodes[i+1].push(n+l);
            nodes[n+l].push(i+1);
        }
    }

    let mut queue = VecDeque::new();
    let mut visited = vec![false; n+m+2];
    queue.push_back(1);
    visited[1] = true;
    while let Some(node) = queue.pop_front() {
        for &next in &nodes[node] {
            if visited[next] {
                continue;
            }
            queue.push_back(next);
            visited[next] = true;
        }
    }
    for i in 1..n+1 {
        if !visited[i] {
            println!("NO");
            return;
        }
    }
    println!("YES");
}


Measured memory_bytes: 24956