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

int main() {
	int N, M;
	cin >> N >> M;
	vector<vector<int>> G1(N);
	vector<pair<int, int>> G2;
	for (int i = 0; i < M; i++) {
		int a, b;
		string s;
		cin >> a >> s >> b;
		a--;
		b--;
		if (s == "<==>") {
			G1[a].push_back(b);
			G1[b].push_back(a);
		} else {
			G2.push_back(make_pair(a, b));
		}
	}
	vector<int> root(N, -1);
	for (int i = 0; i < N; i++) {
		if (root[i] == -1) {
			root[i] = i;
			queue<int> Q;
			Q.push(i);
			while (!Q.empty()) {
				int now = Q.front();
				Q.pop();
				for (int nxt : G1[now]) {
					if (root[nxt] == -1) {
						root[nxt] = i;
						Q.push(nxt);
					}
				}
			}
		}
	}
	bool ans = true;
	for (pair<int, int> p : G2) {
		if (root[p.first] == root[p.second]) {
			ans = false;
		}
	}
	if (!ans) {
		cout << "No" << endl;
	} else {
		vector<vector<int>> G3(N);
		for (pair<int, int> p : G2) {
			int a = root[p.first], b = root[p.second];
			G3[a].push_back(b);
			G3[b].push_back(a);
		}
		vector<int> state(N, -1);
		for (int i = 0; i < N; i++) {
			if (root[i] == i && state[i] == -1) {
				state[i] = 0;
				queue<pair<int, int>> Q;
				Q.push(make_pair(i, 0));
				while (!Q.empty()) {
					int now = Q.front().first;
					int st = Q.front().second;
					Q.pop();
					for (int nxt : G3[now]) {
						if (state[nxt] == -1) {
							state[nxt] = 1 - st;
							Q.push(make_pair(nxt, 1 - st));
						}
					}
				}
			} else if (root[i] != i) {
				state[i] = state[root[i]];
			}
		}
		cout << "Yes" << endl;
		int a = accumulate(state.begin(), state.end(), 0);
		vector<int> out;
		for (int i = 0; i < N; i++) {
			if ((a * 2 >= N && state[i] == 1) || (a * 2 < N && state[i] == 0)) {
				out.push_back(i + 1);
			}
		}
		cout << out.size() << endl;
		for (int i = 0; i < (int)out.size(); i++) {
			cout << out[i] << ' ';
		}
		cout << endl;
	}
}