#include #include using namespace std; using namespace atcoder; //using mint = modint998244353; //const int mod = 998244353; //using mint = modint1000000007; //const int mod = 1000000007; //const int INF = 1e9; //const long long LINF = 1e18; #define rep(i, n) for (int i = 0; i < (n); ++i) #define rep2(i,l,r)for(int i=(l);i<(r);++i) #define rrep(i, n) for (int i = (n-1); i >= 0; --i) #define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i) #define all(x) (x).begin(),(x).end() #define allR(x) (x).rbegin(),(x).rend() #define P pair template inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n, m; cin >> n >> m; struct Edge { int to; int type; }; dsu uf(n); vector>to(n); rep(i, m) { int a, b, c; string s; cin >> a >> s >> b; a--, b--; if ("<==>" == s) c = 0;//同色 else c = 1; to[a].push_back({ b, c }); to[b].push_back({ a, c }); uf.merge(a, b); } vectordp(n); auto dfs = [&](auto self, int v, int p = -1)->bool { if (0 == dp[v])dp[v] = 1; for (auto e : to[v]) { if (0 != dp[e.to]) { if (0 == e.type) { if (dp[e.to] != dp[v])return false; } else { if (dp[e.to] == dp[v])return false; } } else { if (0 == e.type) dp[e.to] = dp[v]; else dp[e.to] = -dp[v]; self(self, e.to, v); } } return true; }; bool chk = true; rep(i, n) { if (0 != dp[i])continue; auto get = dfs(dfs, i); if (!get)chk = false; } if (!chk) { cout << "No" << endl; return 0; } auto g = uf.groups(); vectorans; rep(i, g.size()) { vectorv0, v1; for (auto e : g[i]) { if (-1 == dp[e])v0.push_back(e); else v1.push_back(e); } if (v0.size() < v1.size())swap(v0, v1); rep(i, v0.size())ans.push_back(v0[i]); } if (ans.size() < (n / 2)) { cout << "No" << endl; return 0; } sort(all(ans)); cout << ans.size() << endl; rep(i, ans.size())cout << ans[i] + 1 << " "; cout << endl; return 0; }