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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N,M; cin >> N >> M;
    vector<vector<pair<int,int>>> Graph(N);
    for(int i=0; i<M; i++){
        int u,v; string s;
        cin >> u >> s >> v; u--; v--;
        if(s == "<==>"){
            Graph.at(u).push_back({v,0});
            Graph.at(v).push_back({u,0});                    
        }
        else{
            Graph.at(u).push_back({v,1});
            Graph.at(v).push_back({u,1});
        }
    }

    vector<int> dist(N,-1);
    vector<int> answer;
    for(int i=0; i<N; i++){
        if(dist.at(i) != -1) continue;

        int zero = 0,one = 0;
        vector<int> through;
        queue<int> Q; Q.push(i);
        dist.at(i) = 0;
        while(Q.size()){
            int pos = Q.front(); Q.pop();
            through.push_back(pos);
            int d = dist.at(pos);
            if(d == 0) zero++;
            else one++;

            for(auto [to,cost] : Graph.at(pos)){
                int next = d^cost;
                if(dist.at(to) == -1){dist.at(to) = next; Q.push(to);}
                else if(dist.at(to) != next){cout << "No" << endl; return 0;}
            }
        }

        if(zero >= one){
            for(auto v : through) if(dist.at(v) == 0) answer.push_back(v);
        }
        else{
            for(auto v : through) if(dist.at(v) == 1) answer.push_back(v);
        }
    }

    sort(answer.begin(),answer.end());
    if(answer.size() >= (N+1)/2){
        cout << "Yes" << endl;
        cout << answer.size() << endl;
        for(int i=0; i<answer.size();  i++){
            if(i) cout << " ";
            cout << answer.at(i)+1;  
        }
        cout << endl;
    }
    else{cout << "No" << endl;} 
}