#include #include #include #include #include #include #include #include #define rep(i, a, b) for (int i = int(a); i < int(b); i++) using namespace std; using ll = long long int; // NOLINT using P = pair; // clang-format off #ifdef _DEBUG_ #define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; debug_print(__VA_ARGS__); } while(false) template void debug_print(const T &t, const Ts &...ts) { cerr << t; ((cerr << ", " << ts), ...); cerr << endl; } #else #define dump(...) do{ } while(false) #endif template vector make_v(size_t a, T b) { return vector(a, b); } template auto make_v(size_t a, Ts... ts) { return vector(a, make_v(ts...)); } template bool chmin(T &a, const T& b) { if (a > b) {a = b; return true; } return false; } template bool chmax(T &a, const T& b) { if (a < b) {a = b; return true; } return false; } template void print(const T& t, const Ts&... ts) { cout << t; ((cout << ' ' << ts), ...); cout << '\n'; } template void input(Ts&... ts) { (cin >> ... >> ts); } template istream &operator,(istream &in, T &t) { return in >> t; } struct Inf { template constexpr operator T() { return numeric_limits::max() / 2; } }; // clang-format on class UnionFind { public: vector par; int N; UnionFind(int n) { par.resize(n, -1); N = n; } int Find(int n) { return par[n] < 0 ? n : par[n] = Find(par[n]); } bool Union(int x, int y) { x = Find(x); y = Find(y); if (x == y) return false; if (-par[x] > -par[y]) swap(x, y); par[y] += par[x]; par[x] = y; N--; return true; } bool Same(int x, int y) { return Find(x) == Find(y); } int size(int x) { return -par[Find(x)]; } int size() { return N; } }; int main() { cin.tie(nullptr); ios::sync_with_stdio(false); int n, m; cin >> n >> m; UnionFind uf(2 * n); rep(i, 0, m) { int a, b; cin >> a >> b; a--; b--; uf.Union(a, b + n); uf.Union(a + n, b); } rep(i, 0, n) { if (!uf.Same(i, i + n)) { print("No"); return 0; } } print("Yes"); return 0; }