#include #include using namespace std; using namespace atcoder; using ll = long long; using ull = unsigned long long; using ld = long double; using P = pair; using tp = tuple; template using vec = vector; template using vvec = vector>; #define all(hoge) (hoge).begin(), (hoge).end() #define en '\n' #define rep(i, m, n) for(ll i = (ll)(m); i < (ll)(n); ++i) #define rep2(i, m, n) for(ll i = (ll)(n)-1; i >= (ll)(m); --i) #define REP(i, n) rep(i, 0, n) #define REP2(i, n) rep2(i, 0, n) constexpr long long INF = 1LL << 60; constexpr int INF_INT = 1 << 25; // constexpr long long MOD = (ll)1e9 + 7; constexpr long long MOD = 998244353LL; static const ld pi = 3.141592653589793L; #pragma GCC target("avx2") #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") template inline bool chmin(T &a, T b) { if(a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if(a < b) { a = b; return true; } return false; } struct Edge { int to, rev; ll cap; Edge(int _to, int _rev, ll _cap) : to(_to), rev(_rev), cap(_cap) {} }; typedef vector Edges; typedef vector Graph; void add_edge(Graph &G, int from, int to, ll cap, bool revFlag, ll revCap) { G[from].push_back(Edge(to, (int)G[to].size(), cap)); if(revFlag) G[to].push_back(Edge(from, (int)G[from].size() - 1, revCap)); } void Dijkstra(Graph &g, ll s, vec &d) { // O(|E|log|V|) d.resize(g.size()); REP(i, d.size()) d[i] = INF; d[s] = 0; priority_queue, greater

> q; q.push({0, s}); while(!q.empty()) { auto [dd, v] = q.top(); q.pop(); if(d[v] < dd) continue; for(auto &e : g[v]) { if(d[e.to] > dd + e.cap) { d[e.to] = dd + e.cap; q.push({d[e.to], e.to}); } } } } void solve() { int n, m; cin >> n >> m; int s, t, k; cin >> s >> t >> k; s--; t--; Graph g(n); REP(i, m) { int u, v; cin >> u >> v; u--; v--; add_edge(g, u, v, 1, true, 1); } vec d; Dijkstra(g, s, d); if(d[t] == INF or d[t] > k) { cout << "Unknown" << en; } else if(d[t] % 2 == k % 2) { cout << "Yes" << en; } else { cout << "No" << en; } } int main() { ios::sync_with_stdio(false); cin.tie(0); cout.tie(0); // cout << fixed << setprecision(10); // ll t; // cin >> t; // REP(i, t - 1) { // solve(); // } solve(); return 0; }