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

#include<atcoder/dsu>

int main(){
    
    int n,m;
    cin>>n>>m;
    vector<int> u(m),v(m);
    vector<string> s(m);
    atcoder::dsu uf(n);
    vector<int> p(n,0);
    for(int i = 0;i<m;i++){
        cin>>u[i]>>s[i]>>v[i];
        u[i]--;v[i]--;
        if(s[i]=="<=/=>") {
            p[i] = 1;
            continue;
        }
        uf.merge(u[i],v[i]);
    }
    vector<int> vis(n,0);
    bool ok = true;
    vector<vector<int>> g(n);
    atcoder::dsu u1(2*n);
    for(int i = 0;i<m;i++){
        if(p[i]==0) continue;
        if(uf.same(u[i],v[i])){
            cout<<"No\n";
            return 0;
        }
        int ni = uf.leader(u[i]);
        int nj = uf.leader(v[i]);
        g[ni].push_back(nj);
        g[nj].push_back(ni);
        u1.merge(ni,n+nj);
        u1.merge(nj,n+ni);
    }
    vector<int> use(n,0);
    int all = 0;
    for(int i = 0;i<n;i++) if(u1.same(i,n+i)){
        cout<<"No\n";
        return 0;
    }
    int sum = 0;
    for(int i = 0;i<n;i++){
        if(uf.leader(i)!=i) continue;
        if(vis[i]) continue;
        int a = 0;
        int b = 0;
        vector<int> que;
        que.push_back(i);
        vis[i] = 1;
        for(int j = 0;j<que.size();j++){
            int ni = que[j];
            if(vis[ni]==1) a += uf.size(ni);
            else b += uf.size(ni);
            for(auto&to:g[ni]){
                if(vis[to]) continue;
                que.push_back(to);
                if(vis[ni]==1) vis[to] = 2;
                else vis[to] = 1;
            }
        }
        int ok = 0;
        if(a>=b) ok = 1;
        else ok = 2;
        for(int j = 0;j<que.size();j++){
            int ni = que[j];
            if(vis[ni]==ok) use[ni] = 1;
        }
        sum += max(a,b);
    }
    if(2*sum<n){
        cout<<"No\n";
        return 0;
    }
    vector<int> ans;
    for(int i = 0;i<n;i++){
        int ni = uf.leader(i);
        if(use[ni]) ans.push_back(i);
    }
    cout<<"Yes\n";
    cout<<ans.size()<<endl;
    for(int i = 0;i<ans.size();i++){
        if(i) cout<<" ";
        cout<<ans[i]+1;
    }
    cout<<endl;
        


}