use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).ok();
	let v: Vec<usize> = s.split_whitespace().flat_map(str::parse).collect();
	let mut a = vec![0; v[0]];
	for i in v[2..].chunks(2) {
		a[i[1] - 1] = 1;
	}
	println!("{}", a.iter().filter(|&&x| x == 0).count())
}