#include <bits/stdc++.h>

using namespace std;

#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; --i)
#define ALL(a) (a).begin(), (a).end()
#define Sort(a) (sort((a).begin(), (a).end()))
#define RSort(a) (sort((a).rbegin(), (a).rend()))
#define UNIQUE(a) (a.erase(unique((a).begin(), (a).end()), (a).end()))

typedef long long int ll;
typedef unsigned long long ul;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<char> vc;
typedef vector<string> vst;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef pair<long long, long long> P;

template<class T> long long sum(const T& a){ return accumulate(a.begin(), a.end(), 0LL); }
template<class T> auto min(const T& a){ return *min_element(a.begin(), a.end()); }
template<class T> auto max(const T& a){ return *max_element(a.begin(), a.end()); }

const long long MINF = 0x7fffffffffff;
const long long INF = 0x1fffffffffffffff;
const long long MOD = 998244353;
const long double EPS = 1e-9;
const long double PI = acos(-1);
 
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p){ is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &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(int i = 0; i < (int) v.size(); ++i){ os << v[i] << (i + 1 != (int) v.size() ? " " : ""); } return os; }
template <typename T, typename S> ostream &operator<<(ostream &os, const map<T, S> &mp){ for(auto &[key, val] : mp){ os << key << ":" << val << " "; } return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, queue<T> q){ while(q.size()){ os << q.front() << " "; q.pop(); } return os; }
template <typename T> ostream &operator<<(ostream &os, deque<T> q){ while(q.size()){ os << q.front() << " "; q.pop_front(); } return os; }
template <typename T> ostream &operator<<(ostream &os, stack<T> st){ while(st.size()){ os << st.top() << " "; st.pop(); } return os; }
template <class T, class Container, class Compare> ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq){ while(pq.size()){ os << pq.top() << " "; pq.pop(); } return os; }

template<class T, class U> inline T vin(T& vec, U n) { vec.resize(n); for(int i = 0; i < (int) n; ++i) cin >> vec[i]; return vec; }
template<class T> inline void vout(T vec, string s = "\n"){ for(auto x : vec) cout << x << s; }
template<class... T> void in(T&... a){ (cin >> ... >> a); }
void out(){ cout << '\n'; }
template<class T, class... Ts> void out(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T, class U> void inGraph(vector<vector<T>>& G, U n, U m, bool directed = false){ G.resize(n); for(int i = 0; i < m; ++i){ int a, b; cin >> a >> b; a--, b--; G[a].push_back(b); if(!directed) G[b].push_back(a); } }

template <typename T>
struct WeightedUnionFind{
    vector<int> par, rank, siz;
    vector<T> diff_weight;

    WeightedUnionFind(const int &N, const T &e = 0) : par(N), rank(N), siz(N), diff_weight(N){
        for(int i = 0; i < N; ++i){
            par[i] = i;
            rank[i] = 0;
            siz[i] = 1;
            diff_weight[i] = e;
        }
    }

    int root(const int &x){
        if(par[x] == x){
            return x;
        }
        int rx = root(par[x]);
        diff_weight[x] += diff_weight[par[x]];
        return par[x] = rx;
    }

    T weight(const int &x){
        root(x);
        return diff_weight[x];
    }

    T diff(const int &x, const int &y){
        return weight(y) - weight(x);
    }

    void unite(const int &x, const int &y, T w){
        w += weight(x);
        w -= weight(y);

        int rx = root(x);
        int ry = root(y);
        if(rx == ry) return;

        if(rank[rx] < rank[ry]){
            swap(rx, ry);
            w = -w;
        }

        par[ry] = rx;
        siz[rx] += siz[ry];
        diff_weight[ry] = w;
        if(rank[rx] == rank[ry]) ++rank[rx];
    }

    bool same(const int &x, const int &y){
        int rx = root(x);
        int ry = root(y);
        return rx == ry;
    }

    int size(const int &x){
        return siz[root(x)];
    }
};

ll n, m;

void input(){
    in(n, m);
}

void solve(){
    WeightedUnionFind<ll> uf(n);
    rep(i, m){
        ll u, v;
        string e;
        in(u, e, v); u--, v--;

        ll diff = uf.diff(u, v) % 2;
        diff += 2; diff %= 2;
        if(e == "<==>"){
            if(uf.same(u, v) && diff == 1){
                out("No");
                return;
            }
            uf.unite(u, v, 0);
        }else{
            if(uf.same(u, v) && diff == 0){
                out("No");
                return;
            }
            uf.unite(u, v, 1);
        }
    }
    vector<vll> w0(n), w1(n);
    rep(i, n){
        ll r = uf.root(i);
        ll w = uf.weight(i) % 2;
        w += 2, w %= 2;
        if(w == 1){
            w1[r].push_back(i);
        }else{
            w0[r].push_back(i);
        }
    }
    vll ans;
    rep(i, n){
        if(uf.root(i) == i){
            if(w0.size() >= w1.size()){
                for(auto x : w0[i]){
                    ans.push_back(x + 1);
                }
            }else{
                for(auto x : w1[i]){
                    ans.push_back(x + 1);
                }
            }
        }
    }
    Sort(ans);
    out("Yes");
    out((int) ans.size());
    out(ans);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    
    input();
    solve();
}