#ifndef DEBUG
#pragma GCC target("avx2")
#pragma GCC optimize("Ofast,unroll-loops")
#endif
#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i, n) for (int i = 0; i < n; i++)
#define ALL(a) a.begin(), a.end()
#define ll long long
using namespace std;
using namespace atcoder;
void solve() {
	int n, m;
	cin >> n >> m;
	dsu d(2 * n);
	vector<vector<int>> g(2 * n);
	rep(qqq, m) {
		int i, j;
		string s;
		cin >> i >> s >> j;
		i--, j--;
		if (s.length() == 4) {
			d.merge(i, j);
			d.merge(i + n, j + n);
			g[i].push_back(j);
			g[j].push_back(i);
			g[i + n].push_back(j + n);
			g[j + n].push_back(i + n);
		}
		else {
			d.merge(i, j + n);
			d.merge(i + n, j);
			g[i].push_back(j + n);
			g[j + n].push_back(i);
			g[j].push_back(i + n);
			g[i + n].push_back(j);
		}
	}
	rep(i, n) {
		if (d.same(i, i + n)) {
			cout << "No" << '\n';
			return;
		}
	}
	vector<int> ans;
	vector<bool> used(n);
	queue<int> q;
	rep(st, n) {
		if (used[st]) continue;
		ans.push_back(st);
		used[st] = true;
		q.push(st);
		while (!q.empty()) {
			const int x = q.front();
			q.pop();
			for (int i : g[x]) {
				if (used[i % n]) continue;
				if (i < n) ans.push_back(i);
				used[i % n] = true;
				q.push(i);
			}
		}
	}
	if (ans.size() * 2 < n) {
		cout << "No" << '\n';
		return;
	}
	sort(ALL(ans));
	int size = ans.size();
	cout << "Yes" << '\n';
	cout << size << '\n';
	rep(i, size) cout << ans[i] + 1 << " \n"[i + 1 == size];
}
int main() {
	// srand((unsigned)time(NULL));
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(40);
	solve();
	return 0;
}