#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; template auto range(T s, T e) { return views::iota(s, max(s, e)); } template auto range(T n) { return range(0, n); } template void take(vector& vec, int n) { vec.resize(n); for (int i = 0; i < n; ++i) cin >> vec[i]; } template void sout(const Args &...args) { ((cout << args << ' '), ...); } template void soutn(const Args &...args) { ((cout << args << ' '), ...); cout << '\n'; } template struct In2 { T1 a; T2 b; friend std::istream& operator>>(std::istream& is, In2& obj) { T1 t1; T2 t2; is >> t1 >> t2; obj = {t1, t2}; return is; } }; template struct In3 { T1 a; T2 b; T3 c; friend std::istream& operator>>(std::istream& is, In3& obj) { T1 t1; T2 t2; T3 t3; is >> t1 >> t2 >> t3; obj = {t1, t2, t3}; return is; } }; template struct In4 { T1 a; T2 b; T3 c; T4 d; friend std::istream& operator>>(std::istream& is, In4& obj) { T1 t1; T2 t2; T3 t3; T4 t4; is >> t1 >> t2 >> t3 >> t4; obj = {t1, t2, t3, t4}; return is; } }; #ifdef LOCAL #include #else #define dump(...) ; #endif using EdgeCost = ll; struct E { int fr, to, eid; EdgeCost cost; E(int fr_, int to_, int eid_, EdgeCost cost_) : fr(fr_), to(to_), eid(eid_), cost(cost_) {} friend ostream &operator<<(ostream &os, const E &e) { os << "(" << e.fr << " -> " << e.to << ")"; return os; } }; using V = vector; struct G { int n, e_count; vector adj; G(int n_ = 0) : n(n_), e_count(0), adj(n) {} void add_undirected_edge(int fr, int to, EdgeCost cost = (EdgeCost)1) { assert(0 <= fr && fr < n); assert(0 <= to && to < n); E e1(fr, to, e_count, cost), e2(to, fr, e_count++, cost); adj[fr].push_back(e1); adj[to].push_back(e2); } }; G from_edges(int n, vector> edges) { G g(n); for (auto e : edges) g.add_undirected_edge(e.a - 1, e.b - 1); return g; } namespace { ll n, m, k, s, t; vector> edges; void read() { cin >> n >> m >> k >> s >> t; take(edges, m); } using Bit = bitset<20>; G g; const ll inf = 1LL << 60; EdgeCost shortest_path(int src, int dst) { vector vis(g.n, 0); priority_queue> q; q.push(make_pair((EdgeCost)0, src)); while (!q.empty()) { EdgeCost curr_cost = -q.top().first; int idx = q.top().second; q.pop(); if (vis[idx]) continue; vis[idx] = 1; if (idx == dst) { return curr_cost; } for (auto it : g.adj[idx]) { if (vis[it.to]) continue; if (it.fr == src && it.to == dst) continue; q.push({-(curr_cost + it.cost), it.to}); } } return inf; } ll oddcycle() { ll res = inf; for (int i : range(n)) for (auto e : g.adj[i]) { ll cand = shortest_path(e.fr, e.to); if (cand % 2 == 0) res = min(res, 1 + cand); } return res; } string run() { s--; t--; Bit b; b[s] = 1; g = from_edges(n, edges); if (k % 2) return "Yes"; for (int it : range(2)) { if (ssize(g.adj[s]) > 1) return "Yes"; if (ssize(g.adj[s]) == 1 && g.adj[s][0].to != t) return "Yes"; swap(s, t); } // if (ssize(g.adj[s]) == 0 && ssize(g.adj[t]) == 0) return "No"; ll od = oddcycle(); dump("odd cycle", od); return od + 3 <= k ? "Yes" : "No"; } } // namespace template void exec(F f) { if constexpr (std::is_same_v) f(); else cout << f() << endl; } int main(int argc, char** argv) { cerr << fixed << setprecision(12); cout << fixed << setprecision(12); int testcase = 1; if (argc > 1) testcase = atoi(argv[1]); while (testcase--) { read(); } exec(run); }