// #pragma GCC target("avx") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") #include <bits/stdc++.h> using namespace std; #define rep(i,n) for(int i = 0; i < (int)n; i++) #define FOR(n) for(int i = 0; i < (int)n; i++) #define repi(i,a,b) for(int i = (int)a; i < (int)b; i++) #define all(x) x.begin(),x.end() //#define mp make_pair #define vi vector<int> #define vvi vector<vi> #define vvvi vector<vvi> #define vvvvi vector<vvvi> #define pii pair<int,int> #define vpii vector<pair<int,int>> template<typename T> bool chmax(T &a, const T b) {if(a<b) {a=b; return true;} else {return false;}} template<typename T> bool chmin(T &a, const T b) {if(a>b) {a=b; return true;} else {return false;}} using ll = long long; using ld = long double; using ull = unsigned long long; const ll INF = numeric_limits<long long>::max() / 2; const ld pi = 3.1415926535897932384626433832795028; const ll mod = 998244353; int dx[] = {1, 0, -1, 0, -1, -1, 1, 1}; int dy[] = {0, 1, 0, -1, -1, 1, -1, 1}; #include"atcoder/all" void solve() { int n, m; cin >> n >> m; atcoder::two_sat sat(n); FOR(m) { int u, v; string s; cin >> u >> s >> v; --u; --v; if(s == "<==>") { sat.add_clause(u, true, v, false); sat.add_clause(u, false, v, true); }else { sat.add_clause(u, true, v, true); sat.add_clause(u, false, v, false); } } bool satisfy = sat.satisfiable(); if(!satisfy) { cout << "No" << endl; return; } vector<bool> ans = sat.answer(); cout << "Yes" << endl; int sz = (int)count(all(ans), true); if(2*sz >= n) { cout << sz << endl; bool flag = true; FOR(n) if(ans[i]) { if(!flag) cout << " "; flag = false; cout << i+1; } cout << "\n"; }else { cout << n-sz << endl; bool flag = true; FOR(n) if(!ans[i]) { if(!flag) cout << " "; flag = false; cout << i+1; } cout << "\n"; } } signed main() { cin.tie(nullptr); ios::sync_with_stdio(false); solve(); return 0; }