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 a = (0..w[1].parse().unwrap()).fold(0, |a, i| {
		(0..w[0].parse().unwrap())
			.fold(1, |c, j| c + if &w[j + 2][i..=i] == "x" { 1 } else { 0 })
			.max(a)
	});
	println!("{a}")
}