use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).ok();
	let w: Vec<_> = s.split_whitespace().collect();
	let (n, m): (usize, usize) = (w[0].parse().unwrap(), w[1].parse().unwrap());
	let a = (0..m).fold(0, |a, i| {
		let mut c = 1;
		for j in 0..n {
			if &w[j + 2][i..=i] == "x" {
				c += 1;
			}
		}
		a.max(c)
	});
	println!("{a}")
}