// 嘘解法WA

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

int main() {
	int n, m;
	cin >> n >> m;
	assert(2 <= n && n <= 100000);
	assert(1 <= m && m <= min(100000, n * (n - 1)));
	vector<pair<int, int>> same, notsame;
	for (int i = 0; i < m; i++) {
		int x, y; string e;
		cin >> x >> e >> y;
		x--; y--;
		if (e == "<==>") same.push_back({x, y});
		else notsame.push_back({x, y});
	}
	dsu uf(n);
	// 「同じ」の要望についてUnionFindの辺を張る
	for (auto i: same) {
		uf.merge(i.first, i.second);
	}
	// 「同じ」の連結成分に「違う」がある場合はだめ
	for (auto i: notsame) {
		if (uf.same(i.first, i.second)) {
			cout << "No\n";
			return 0;
		}
	}
	// 連結成分を求める
	auto gr = uf.groups();
	int ns = gr.size();
	vector<vector<int>> lds(ns);
	map<int, int> ld; // 頂点→leaderの番号
	for (int i = 0; i < ns; i++) {
		lds[i] = gr[i];
		for (int j: gr[i]) ld[j] = i;
	}
	// 「違う」の辺を張る
	vector<vector<int>> g(ns);
	for (auto i: notsame) {
		int ldx = ld[i.first], ldy = ld[i.second];
		g[ldx].push_back(ldy);
		g[ldy].push_back(ldx);
	}
	// 二部グラフ判定
	vector<int> col(ns, -1);
    for (int u = 0; u < ns; u++) {
        if (col[u] != -1) {
        	continue;
        }
        col[u] = 0;
        queue<int> q;
        q.push(u);
        while (!q.empty()) {
            int v = q.front();
            q.pop();
            for (auto nv : g[v]) {
                if (col[nv] != -1) {
                    if (col[nv] == col[v]) {
                    	cout << "No\n";
                    	return 0;
                    }
                    continue;
                }
                col[nv] = 1 - col[v];
                q.push(nv);
            }
        }
    }
    vector<int> c0, c1;
    for (int i = 0; i < n; i++) {
    	if (col[ld[i]]) c1.push_back(i + 1);
    	else c0.push_back(i + 1);
    }
    cout << "Yes\n";
    // if (c0.size() * 2 >= n) {
    	int c0s = c0.size();
    	cout << c0s << '\n';
    	for (int i = 0; i < c0s - 1; i++) {
    		cout << c0[i] << ' ';
    	}
    	cout << c0[c0s - 1] << '\n';
    // }
    /*
    else {
    	int c1s = c1.size();
    	cout << c1s << '\n';
    	for (int i = 0; i < c1s - 1; i++) {
    		cout << c1[i] << ' ';
    	}
    	cout << c1[c1s - 1] << '\n';
    }
    */
}