#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

int main(){
	int n; cin >> n;
	two_sat sat(n);
	int m; cin >> m;
	rep(i,0,m){
		int x;
		string s;
		int y;
		cin >> x >> s >> y;
		x--; y--;
		if (s == "<==>"){
			sat.add_clause(x, 0, y, 1);
			sat.add_clause(y, 0, x, 1);
		}else{
			sat.add_clause(x, 1, y, 1);
			sat.add_clause(x, 0, y, 0);
			sat.add_clause(y, 0, x, 0);
			sat.add_clause(y, 1, x, 1);
		}
	}
	bool f = sat.satisfiable();
	if (!f){
		cout << "No\n";
		return 0;
	}

	vector<bool> g = sat.answer();
	int cnt = 0;
	rep(i,0,n){
		if (g[i]) cnt++;
	}
	if (cnt * 2 < n){
		rep(i,0,n){
			if (g[i] == 0){
				g[i] = 1;
			}else{
				g[i] = 0;
			}
		}
	}
	vector<int> ans;
	rep(i,0,n){
		if (g[i]){
			ans.push_back(i);
		}
	}
	
	cout << "Yes\n";
	int k = ans.size();
	cout << k << '\n';
	rep(i,0,k){
		cout << ans[i] + 1;
		if (i == k-1) cout << '\n';
		else cout << ' ';
	}
}