#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

using mint = modint998244353;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

int main() {
    ll N, M;
    cin >> N >> M;
    vector<ll> u(M);
    vector<string> E(M);
    vector<ll> v(M);
    for (ll i = 0; i < M; i++){
        cin >> u[i] >> E[i] >> v[i];
        u[i]--;
        v[i]--;
    }
    vector<vector<pll>> graph(N, vector<pll>(0));
    rep(i, M){
        ll cost = 0;
        if (E[i].size() == 5) cost++;
        graph[u[i]].push_back(make_pair(v[i], cost));
        graph[v[i]].push_back(make_pair(u[i], cost));
    }
    vector<ll> col(N, -1);
    for (ll i = 0; i < N; i++){
        if (col[i] != -1){
            continue;
        }
        vector<ll> es;
        queue<ll> que;
        que.push(i);
        es.push_back(i);
        col[i] = 0;
        ll white = 1;
        ll black = 0;

        while (que.size()){
            ll p = que.front();
            que.pop();
            for (pll px: graph[p]){
                ll nx = px.first;
                ll nc = px.second;
                if (col[nx] != -1){
                    if (nc == 1 && col[nx] == col[p]){
                        cout << "No" << endl;
                        return 0;
                    }
                    else if (nc == 0 && col[nx] != col[p]){
                        cout << "No" << endl;
                        return 0;
                    }
                    continue;
                }
                que.push(nx);
                es.push_back(nx);
                if (nc == 0){
                    if (col[p] == 0){
                        col[nx] = 0;
                        white++;
                    }
                    else{
                        col[nx] = 1;
                        black++;
                    }
                }
                else{
                    if (col[p] == 0){
                        col[nx] = 1;
                        black++;
                    }
                    else{
                        col[nx] = 0;
                        white++;
                    }
                }
            }
        }
        if (white < black){
            for (ll x: es){
                col[x] ^= 1;
            }
        }
    }
    vector<ll> ans;
    rep(i, N){
        if (col[i] == 0) ans.push_back(i);
    }
    cout << "Yes" << endl;
    ll L = ans.size();
    cout << L << endl;
    for (ll i = 0; i < L; i++){
        cout << ans[i] + 1;
        if (i < L - 1) cout << " ";
    }
    cout << endl;
}