#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;

ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second << "\n"; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template <typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

int main(){
	int n, m;
	cin >> n >> m;
	dsu uf(n);
	vector<vector<pair<int, int>>> G(n);
	rep(i, m){
		int u, v;
		string s;
		cin >> u >> s >> v;
		u--; v--;
		int e = -1;
		if(s == "<=/=>") e = 1;
		if(s == "<==>") e = 0;
		G[u].emplace_back(v, e);
		G[v].emplace_back(u, e);
		uf.merge(u, v);
	}
	vi c(n, -1);
	bool success = true;
	auto dfs = [&](int from, int prev, auto dfs) -> void{
		for(auto [to, e] : G[from]){
			if(from == prev) continue;
			if(c[to] != -1){
				if(c[to] != c[from] ^ e) success = false;
				continue;
			}
			c[to] = c[from] ^ e;
			dfs(to, from, dfs);
		}
	};
	rep(i, n){
		if(c[i] == -1){
			c[i] = 0;
			dfs(i, -1, dfs);
		}
	}
	if(!success){
		cout << "No\n";
		return 0;
	}
	auto groups = uf.groups();
	int mx = 0;
	vi ans;
	for(auto& v : groups){
		vi d(2);
		for(int x : v) d[c[x]]++;
		if(d[0] >= d[1]){
			mx += d[0];
			for(int x : v) if(c[x] == 0) ans.push_back(x + 1);
		}else{
			mx += d[1];
			for(int x : v) if(c[x] == 1) ans.push_back(x + 1);
		}
	}
	if(mx * 2 >= n){
		cout << "Yes\n";
		cout << mx << "\n";
		cout << ans;
	}else cout << "No\n";
	return 0;
}