#![allow(unused_imports, dead_code, unused_macros, unused_variables, non_snake_case, unused_parens)]
use std::cmp::{min,max,Ordering,Reverse};
use std::mem::swap;
use std::collections::{VecDeque,LinkedList,HashMap,BTreeMap,HashSet,BTreeSet,BinaryHeap};

const MOD:u64 = 1_000_000_007;
const INF:i64 = 0x7fff_ffff_ffff_ffff;

macro_rules! min {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::min($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::min($a, min!($($rest),+))}};}
macro_rules! max {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::max($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::max($a, max!($($rest),+))}};}
macro_rules! mulvec {($x:expr; $s:expr) => {vec![$x; $s]};($x:expr; $s0:expr; $( $s:expr );+) => {mulvec![vec![$x; $s0]; $( $s );+ ]};}


fn solve() {
	input! {
		n : usize,
		m : usize,
		iej: [(usize,String,usize);m],
	}
	let mut uf = UnionFind::new(n*2);
	for (i,e,j) in iej {
		if e == "<==>" {
			uf.unite(i-1, j-1);
			uf.unite(i-1+n, j-1+n);
		}else{
			uf.unite(i-1, j-1+n);
			uf.unite(i-1+n, j-1);
		}
	}
	let flg = (0..n).all(|i| !uf.same(i, i+n));
	if flg {
		println!("Yes");
		let mut a = vec![];
		let mut b = vec![];
		for i in 0..n {
			if uf.same(i, 0) {
				a.push(i+1);
			}else if uf.same(i+n, 0){
				b.push(i+1);
			}else{
				a.push(i+1);
				uf.unite(0, i);
			}
		}
		if a.len() >= b.len() {
			println!("{}", a.len());
			println!("{}", a.iter().map(std::string::ToString::to_string).collect::<Vec<_>>().join(" "));
		}else{
			println!("{}", b.len());
			println!("{}", b.iter().map(std::string::ToString::to_string).collect::<Vec<_>>().join(" "));
		}
	}else{
		println!("No");
	}
}

fn main() {
	std::thread::Builder::new()
		.stack_size(128 * 1024 * 1024)
		.spawn(|| solve()).unwrap()
		.join().unwrap();
}

pub struct UnionFind {
	parents: Vec<i32>,
}
impl UnionFind {
	pub fn new(n: usize) -> Self {
		UnionFind {
			parents: vec![-1_i32; n],
		}
	}

	pub fn find(&mut self, x: usize) -> usize {
		if self.parents[x] < 0 {
			return x;
		}
		self.parents[x] = self.find(self.parents[x] as usize) as i32;
		self.parents[x] as usize
	}

	pub fn same(&mut self, x:usize, y:usize) -> bool {
		self.find(x) == self.find(y)
	}

	pub fn unite(&mut self, x:usize, y:usize) -> bool {
		let mut x = self.find(x) as usize;
		let mut y = self.find(y) as usize;
		if x == y {
			return false;
		}
		if self.parents[x] > self.parents[y] {
			std::mem::swap(&mut x, &mut y);
		}
		self.parents[x] += self.parents[y];
		self.parents[y] = x as i32;
		true
	}

	pub fn size(&mut self, x:usize) -> usize {
		let parent = self.find(x);
		(-self.parents[parent]) as usize
	}
}



mod _input {
	// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
	#[macro_export]
	macro_rules! input {
		(source = $s:expr, $($r:tt)*) => {
			let mut iter = $s.split_whitespace();
			let mut next = || { iter.next().unwrap() };
			input_inner!{next, $($r)*}
		};
		($($r:tt)*) => {
			let stdin = std::io::stdin();
			let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
			let mut next = move || -> String{
				bytes
					.by_ref()
					.map(|r|r.unwrap() as char)
					.skip_while(|c|c.is_whitespace())
					.take_while(|c|!c.is_whitespace())
					.collect()
			};
			input_inner!{next, $($r)*}
		};
	}
	#[macro_export]
	macro_rules! input_inner {
		($next:expr) => {};
		($next:expr, ) => {};

		($next:expr, $var:ident : $t:tt $($r:tt)*) => {
			let $var = read_value!($next, $t);
			input_inner!{$next $($r)*}
		};
	}
	#[macro_export]
	macro_rules! read_value {
		($next:expr, ( $($t:tt),* )) => {
			( $(read_value!($next, $t)),* )
		};

		($next:expr, [ $t:tt ; $len:expr ]) => {
			(0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
		};

		($next:expr, chars) => {
			read_value!($next, String).chars().collect::<Vec<char>>()
		};

		($next:expr, usize1) => {
			read_value!($next, usize) - 1
		};

		($next:expr, $t:ty) => {
			$next().parse::<$t>().expect("Parse error")
		};
	}
}