#include <bits/stdc++.h>
#include <atcoder/all>
#define SELECTER(_1,_2,_3,SELECT,...) SELECT
#define rep1(i,n) for(int i=0;i<(int)n;++i)
#define rep2(i,a,n) for(int i=(int)a;i<(int)n;++i)
#define rep(...) SELECTER(__VA_ARGS__,rep2,rep1)(__VA_ARGS__)
#define RSELECTER(_1, _2, _3, RSELECT, ...) RSELECT
#define rrep1(i,n) for(int i=(int)n-1;i>=0;--i)
#define rrep2(i,a,n) for(int i=(int)n-1;i>=(int)a;--i)
#define rrep(...) RSELECTER(__VA_ARGS__, rrep2, rrep1)(__VA_ARGS__)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fi first
#define se second
#define PrintR LogOutput
#ifdef _DEBUG
#define Log(...) LogOutput(__VA_ARGS__)
#else
#define Log(...)
#endif
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
using pii=pair<int,int>;
using pll=pair<long long,long long>;
using pdd=pair<long double,long double>;
using tp=tuple<int,int,int>;
using tpll=tuple<ll,ll,ll>;
using veci=vector<int>;
using vecpii=vector<pair<int,int>>;
using vecll=vector<long long>;
using vecpll=vector<pair<long long,long long>>;
using vecpdd=vector<pair<long double,long double>>;
using vecs=vector<string>;
using vecb=vector<bool>;
using vecd=vector<long double>;
using vectp=vector<tp>;
using vectpll=vector<tpll>;
using mint=modint998244353;
using mint10=modint1000000007;
template<typename T, typename S>
istream& operator>>(istream& in, pair<T, S>& a){return in >> a.first >> a.second;}
template<typename T, typename S>
ostream& operator<<(ostream& out, const pair<T, S>& a){return out << a.first << ' ' << a.second;}
ostream& operator<<(ostream& out, const mint& a){return out << a.val();}
ostream& operator<<(ostream& out, const mint10& a){return out << a.val();}
ostream& operator<<(ostream& out, const modint& a){return out << a.val();}
template<typename T>
ostream& operator<<(ostream& out, const vector<T>& d){for(int i = 0 ; i < d.size() ; ++i) out << d[i] << (i == d.size() - 1 ? "" : " "); return out;}
template<typename T, typename S>
pair<T, S> operator+(const pair<T, S>& a, const pair<T, S>& b){return {a.fi + b.fi, a.se + b.se};}
template<typename T, typename S>
pair<T, S> operator-(const pair<T, S>& a, const pair<T, S>& b){return {a.fi - b.fi, a.se - b.se};}
template<class T> inline bool chmax(T& a,T b){if(a<b) {a=b;return true;} return false;}
template<class T> inline bool chmin(T& a,T b){if(a>b) {a=b;return true;} return false;}
bool Judge(int i, int j, int h, int w){return i < 0 || j < 0 || i >= h || j >= w;}
bool PrintA(int i){cout<<(i ? "Yes" : "No")<<endl;return i;}

constexpr ll INF=numeric_limits<ll>::max() / 4;
constexpr int inf=numeric_limits<int>::max() / 2;
constexpr ll MOD=998244353;
const int vi[] = {0, 1, 0, -1}, vj[] = {1, 0, -1, 0};

template<typename... Args>
void LogOutput(Args&&... args){
	stringstream ss;
	((ss << args << ' '), ...);
	cout << ss.str().substr(0, ss.str().length() - 1) << endl;
}
template<typename T>
void LogOutput(vector<vector<T>>& data){for(auto d : data) LogOutput(d);}

int main(){
	ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int n, m;cin>>n>>m;
	vector<veci> g(n);
	vector<veci> g2(n);
	rep(i, m){
		int a, b;
		string s;cin>>a>>s>>b;
		a--, b--;
		if(s == "<==>"){
			g2[a].push_back(b);
			g2[b].push_back(a);
		}else{
			g[a].push_back(b);
			g[b].push_back(a);
		}
	}
	queue<int> q;
	veci used(n, -1);
	veci used2(n, -1);
	veci b;
	auto f = [&q, &g, &g2, &b](veci& used, int i, int c = 1) -> int {
		q.push(i);
		if(c) b.push_back(i);
		while(q.size()){
			int v = q.front(); q.pop();
			for(int nv : g[v]){
				if(used[nv] == -1){
					used[nv] = used[v] ^ 1;
					if(c) b.push_back(nv);
					q.push(nv);
				}else if(used[nv] == used[v]){
					while(q.size()) q.pop();
					return 0;
				}
			}
			for(int nv : g2[v]){
				if(used[nv] == -1){
					used[nv] = used[v];
					if(c) b.push_back(nv);
					q.push(nv);
				}else if(used[nv] != used[v]){
					while(q.size()) q.pop();
					return 0;
				}
			}
		}
		return 1;
	};
	rep(i, n) if(used[i] == -1){
		used[i] = 1;
		used2[i] = 0;
		int r = f(used, i);
		int r2 = f(used2, i, 0);
		if(r == 0 && r2 == 0){
			cout<<"No"<<endl;
			return 0;
		}else if(r == 0){
			rep(i, b.size()) used[b[i]] = used2[b[i]];
		}else if(r2){
			int cnt = 0, cnt2 = 0;
			rep(i, b.size()){
				cnt += used[b[i]];
				cnt2 += used2[b[i]];
			}
			if(cnt < cnt2) rep(i, b.size()) used[b[i]] = used2[b[i]];
		}
		b.clear();
	}
	cout<<"Yes"<<endl;
	veci a;
	rep(i, n) if(used[i]) a.push_back(i + 1);
	cout<<a.size()<<endl;
	PrintR(a);
}