#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n, m;
    cin >> n >> m;
    dsu uf(n);
    vector<vector<int>> g(n);
    vector<pair<int,int>> e;
    rep(i,m){
        int a, b;
        string s;
        cin >> a >> s >> b;
        --a;--b;
        if(s=="<==>"){
            uf.merge(a,b);
        }
        else{
            e.emplace_back(a,b);
        }
    }   
    dbg(uf.groups());
    for(auto [d,f] : e){
        if(uf.same(d,f)){
            cout << "No" << endl;
            return 0;
        }
        g[uf.leader(d)].push_back(uf.leader(f));
        g[uf.leader(f)].push_back(uf.leader(d));
    }
    dbg(g);
    //二部グラフ判定
    vector<int> color(n, -1);
    auto dfs = [&](auto dfs, int u, int c) -> bool {
        color[u] = c;
        for(int v : g[u]){
            if(color[v] == c) return false;
            if(color[v]==-1 && !dfs(dfs,v, c^1)) return false;
        }
        return true;
    };
    vector<bool> vis(n);
    vector<vector<int>> cnt(2);
    auto dfs2 = [&](auto dfs2, int u) -> void {
        vis[u] = true;
        cnt[color[u]].push_back(u);
        for(int v : g[u]){
            if(!vis[v]) dfs2(dfs2,v);
        }
    };
    int ans = 0;
    set<int> t;
    rep(i,n){
        if(color[i]==-1 && uf.leader(i)==i){
            if(!dfs(dfs, i,0)){
                cout<<"No" << endl;
                return 0;
            }
            cnt.clear();
            dfs2(dfs2,i);
            int sum0, sum1 = 0;
            for(int c : cnt[0]) sum0 += uf.size(c);
            for(int c : cnt[1]) sum1 += uf.size(c);
            if(sum0>=sum1) {
                for(int c : cnt[0]) {
                    t.insert(c);
                }
            }
            else{
                for(int c : cnt[1]) t.insert(c);
            }
            ans += max(sum0,sum1);
        }
    }
    if(ans>=(n+1)/2){
        cout << "Yes" << endl;
        cout << ans << endl;
        rep(i,n){
            if(t.count(uf.leader(i))) cout << i + 1 << " ";
        }
        cout << endl;
        return 0;
    }
    cout << "No" << endl;
    return 0;
}