#include <bits/stdc++.h>
using namespace std;
#define overload2(a, b, c, ...) c
#define overload3(a, b, c, d, ...) d
#define overload4(a, b, c, d, e ...) e
#define overload5(a, b, c, d, e, f ...) f
#define overload6(a, b, c, d, e, f, g ...) g
#define fast_io ios::sync_with_stdio(false); cin.tie(nullptr);
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
typedef long long ll;
typedef long double ld;
#define chmin(a,b) a = min(a,b);
#define chmax(a,b) a = max(a,b);
#define bit_count(x) __builtin_popcountll(x)
#define leading_zero_count(x) __builtin_clz(x)
#define trailing_zero_count(x) __builtin_ctz(x)
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) a / gcd(a,b) * b
#define rep(...) overload3(__VA_ARGS__, rrep, rep1)(__VA_ARGS__)
#define rep1(i,n) for(int i = 0 ; i < n ; i++)
#define rrep(i,a,b) for(int i = a ; i < b ; i++)
#define repi(it,S) for(auto it = S.begin() ; it != S.end() ; it++)
#define pt(a) cout << a << endl;
#define print(...) printall(__VA_ARGS__);
#define debug(a) cout << #a << " " << a << endl;
#define all(a) a.begin(), a.end()
#define endl "\n";
#define v1(T,n,a) vector<T>(n,a)
#define v2(T,n,m,a) vector<vector<T>>(n,v1(T,m,a))
#define v3(T,n,m,k,a) vector<vector<vector<T>>>(n,v2(T,m,k,a))
#define v4(T,n,m,k,l,a) vector<vector<vector<vector<T>>>>(n,v3(T,m,k,l,a))
template<typename T,typename U>istream &operator>>(istream&is,pair<T,U>&p){is>>p.first>>p.second;return is;}
template<typename T,typename U>ostream &operator<<(ostream&os,const pair<T,U>&p){os<<p.first<<" "<<p.second;return os;}
template<typename T>istream &operator>>(istream&is,vector<T>&v){for(T &in:v){is>>in;}return is;}
template<typename T>ostream &operator<<(ostream&os,const vector<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"");}return os;}
template<typename T>istream &operator>>(istream&is,vector<vector<T>>&v){for(T &in:v){is>>in;}return is;}
template<typename T>ostream &operator<<(ostream&os,const vector<vector<T>>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?"\n":"");}return os;}
template<typename T>ostream &operator<<(ostream&os,const set<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"");}return os;}
template<typename T>ostream &operator<<(ostream&os,const multiset<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"");}return os;}
template<class... Args> void printall(Args... args){for(auto i:initializer_list<common_type_t<Args...>>{args...}) cout<<i<<" ";cout<<endl;}

int n, m;
vector<vector<pair<int,int>>> G;
vector<int> d;

pair<vector<int>,vector<int>> bfs(int s){
    queue<int> que;
    que.push(s);
    d[s] = 0;
    vector<int> V, U;
    while(!que.empty()){
        int v = que.front(); que.pop();
        if(d[v] == 0) V.push_back(v);
        else U.push_back(v);
        for(auto[u, c] : G[v]){
            int nval = abs(d[v] - c);
            if(d[u] == -1){
                d[u] = nval;
                que.push(u);
                continue;
            }
            else{
                if(d[u] == nval) continue;
                return {{}, {}};
            }
        }
    }
    return {V, U};
}

void solve(){
    cin >> n >> m;
    G = vector<vector<pair<int,int>>>(n);
    d = vector<int>(n,-1);
    rep(i,m){
        int a, b;
        string E;
        cin >> a >> E >> b;
        a--; b--;
        if(E.size() == 5){
            G[a].push_back({b,1});
            G[b].push_back({a,1});
        }
        else{
            G[a].push_back({b,0});
            G[b].push_back({a,0});
        }
    }
    vector<int> res;
    rep(i,n){
        if(d[i] == -1) {
            auto [v,u] = bfs(i);
            if(v.empty() && u.empty()){
                pt("No")
                return;
            }
            if(v.size() > u.size()) swap(v,u);
            for(int x : u) res.push_back(x+1);
        }
    }
    if(res.size() > n / 2){
        sort(all(res));
        pt("Yes")
        pt(res.size());
        pt(res)
        return;
    }
    pt("No")
}

int main(){
    fast_io
    int t = 1;
    // cin >> t;
    rep(i,t) solve();
}