#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;
    two_sat ts(n);
    rep(i,m){
        int a, b;
        string s;
        cin >> a >> s >> b;
        --a;--b;
        if(s=="<==>"){
            ts.add_clause(a, 0, b, 1);
            ts.add_clause(a, 1, b, 0);
        }
        else{
            ts.add_clause(a, 1, b, 1);
            ts.add_clause(a, 0, b, 0);
        }
    }   
    bool f = ts.satisfiable();
    if(f){
        cout << "Yes" << endl;
        auto vs = ts.answer();
        int s = accumulate(vs.begin(),vs.end(),0);
        vector<int> ans;
        if(s>=(n+1)/2){
            rep(i,n) if(vs[i]) ans.push_back(i);
        }
        else{
            rep(i,n) if(!vs[i]) ans.push_back(i);
        }
        cout << ans.size() << endl;
        rep(i,ans.size()){
            cout << ans[i]+1;
            if(i==ans.size()-1) cout << endl;
            else cout << " ";
        }
    }   
    else{
        cout << "No" << endl;
    }
    return 0;
}