use std::collections::VecDeque;

fn topologycal_sort(paths: &Vec<Vec<usize>>) -> Vec<usize> {
    let n = paths.len();
    let mut ret = vec![];
    let mut ins = vec![0usize; n];
    for i in 0..n {
        for &v in paths[i].iter() {
            ins[v] += 1;
        }
    }
    let mut que = VecDeque::new();
    for i in 0..n {
        if ins[i] == 0 {
            que.push_back(i);
        }
    }
    while let Some(x) = que.pop_back() {
        ret.push(x);
        for &v in paths[x].iter() {
            ins[v] -= 1;
            if ins[v] == 0 {
                que.push_back(v);
            }
        }
    }
    ret
}


fn main() {
    let mut nm = String::new();
    std::io::stdin().read_line(&mut nm).ok();
    let nm: Vec<usize> = nm.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nm[0];
    let m = nm[1];
    let mut paths = vec![vec![]; n];
    let mut revpaths = vec![0usize; n];
    for _ in 0..m {
        let mut temp = String::new();
        std::io::stdin().read_line(&mut temp).ok();
        let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
        let g = temp[0]-1;
        let mut h = String::new();
        std::io::stdin().read_line(&mut h).ok();
        let h: Vec<usize> = h.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
        for &v in h.iter() {
            let v = v-1;
            paths[v].push(g);
            revpaths[g] += 1;
        }
    }

    let mut result = 0;
    let orders = topologycal_sort(&paths);
    for &u in orders.iter() {
        if result >= revpaths[u] {
            result += 1;
        }
    }
    println!("{}", result);
}