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use std::iter;

fn main() {
    let mut lines = std::io::stdin().lines();
    let kn_1 = lines
        .next()
        .unwrap()
        .unwrap()
        .split_whitespace()
        .map(|x| str::parse(x).unwrap())
        .collect::<Vec<i32>>();
    let descs = iter::once((0..kn_1[1]).map(|_| 0).collect())
        .chain((2..=kn_1[0]).map(|_| {
            lines
                .next()
                .unwrap()
                .unwrap()
                .split_whitespace()
                .skip(1)
                .map(|x| str::parse(x).unwrap())
                .collect()
        }))
        .collect::<Vec<Vec<i32>>>();
    let mut needs = descs
        .iter()
        .map(|x| x.iter().map(|_| 0).collect())
        .collect::<Vec<Vec<i32>>>();
    for f in needs[kn_1[0] as usize - 1].iter_mut() {
        *f = 1;
    }
    // eprintln!("{:?} {:?}", descs, needs);
    for i in (0..(kn_1[0] - 1)).rev() {
        let (l, r) = needs.split_at_mut(i as usize + 1);
        let this = l.last_mut().unwrap();
        let next = r.first().unwrap();
        // eprintln!("{:?} {:?}", this, next);
        for (desc, need) in descs[i as usize + 1].iter().copied().zip(next.iter()) {
            if desc > 0 {
                this[desc as usize - 1] += need;
            }
        }
        // eprintln!("{:?} {:?}", this, next);
        for f in this.iter_mut() {
            if *f == 0 {
                *f = 1;
            }
        }
        // eprintln!("{:?} {:?}", this, next);
    }
    println!(
        "{}",
        needs.iter().map(|x| x.iter().sum::<i32>()).max().unwrap()
    );
}