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

template<bool Enable_small_to_large = true>
struct disjoint_set{
	int n, _classes;
	vector<int> p;
	disjoint_set(int n): n(n), _classes(n), p(n, -1){ }
	int make_set(){
		p.push_back(-1);
		++ _classes;
		return n ++;
	}
	int classes() const{
		return _classes;
	}
	int root(int u){
		return p[u] < 0 ? u : p[u] = root(p[u]);
	}
	bool share(int a, int b){
		return root(a) == root(b);
	}
	int size(int u){
		return -p[root(u)];
	}
	bool merge(int u, int v){
		u = root(u), v = root(v);
		if(u == v) return false;
		-- _classes;
		if constexpr(Enable_small_to_large) if(p[u] > p[v]) swap(u, v);
		p[u] += p[v], p[v] = u;
		return true;
	}
	bool merge(int u, int v, auto act){
		u = root(u), v = root(v);
		if(u == v) return false;
		-- _classes;
		bool swapped = false;
		if constexpr(Enable_small_to_large) if(p[u] > p[v]) swap(u, v), swapped = true;
		p[u] += p[v], p[v] = u;
		act(u, v, swapped);
		return true;
	}
	void clear(){
		_classes = n;
		fill(p.begin(), p.end(), -1);
	}
	vector<vector<int>> group_up(){
		vector<vector<int>> g(n);
		for(auto i = 0; i < n; ++ i) g[root(i)].push_back(i);
		g.erase(remove_if(g.begin(), g.end(), [&](auto &s){ return s.empty(); }), g.end());
		return g;
	}
};

int main(){
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(ios::badbit | ios::failbit);
	int n, m;
	cin >> n >> m;
	disjoint_set dsu(n << 1);
	for(auto i = 0; i < m; ++ i){
		int u, v;
		string type;
		cin >> u >> type >> v, -- u, -- v;
		for(auto t = 0; t < 2; ++ t){
			dsu.merge(u << 1 | t, v << 1 | (t ^ (type == string("<=/=>"))));
		}
	}
	vector<int> res, vis(n);
	for(auto g: dsu.group_up()){
		if(vis[g[0] >> 1]){
			continue;
		}
		for(auto u2: g){
			vis[u2 >> 1] = true;
		}
		if(dsu.share(g[0], g[0] ^ 1)){
			cout << "No\n";
			return 0;
		}
		array<int, 2> cnt{};
		for(auto u2: g){
			++ cnt[u2 & 1];
		}
		int rem = cnt[0] < cnt[1];
		for(auto u2: g){
			if(u2 % 2 == rem){
				res.push_back(u2 >> 1);
			}
		}
	}
	if((int)res.size() * 2 >= n){
		sort(res.begin(), res.end());
		cout << "Yes\n" << (int)res.size() << "\n";
		for(auto i = 0; i < (int)res.size(); ++ i){
			cout << res[i] + 1;
			if(i < (int)res.size() - 1){
				cout << " ";
			}
		}
		cout << "\n";
	}
	else{
		cout << "No\n";
	}
	return 0;
}

/*

*/

////////////////////////////////////////////////////////////////////////////////////////
//                                                                                    //
//                                   Coded by Aeren                                   //
//                                                                                    //
////////////////////////////////////////////////////////////////////////////////////////