// #pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
// #include <x86intrin.h>
using namespace std;
#if __cplusplus >= 202002L
using namespace numbers;
#endif

template<bool Enable_small_to_large = true>
struct disjoint_set{
	int n, _group_count;
	vector<int> p;
	vector<list<int>> group;
	disjoint_set(){ }
	disjoint_set(int n): n(n), _group_count(n), p(n, -1), group(n){ assert(n >= 0);
		for(auto i = 0; i < n; ++ i) group[i] = {i};
	}
	int make_set(){
		p.push_back(-1);
		group.push_back(list<int>{p});
		++ _group_count;
		return n ++;
	}
	int root(int u){
		return p[u] < 0 ? u : p[u] = root(p[u]);
	}
	bool share(int a, int b){
		return root(a) == root(b);
	}
	int size(int u){
		return -p[root(u)];
	}
	bool merge(int u, int v){
		u = root(u), v = root(v);
		if(u == v) return false;
		-- _group_count;
		if constexpr(Enable_small_to_large) if(p[u] > p[v]) swap(u, v);
		p[u] += p[v], p[v] = u;
		group[u].splice(group[u].end(), group[v]);
		return true;
	}
	bool merge(int u, int v, auto act){
		u = root(u), v = root(v);
		if(u == v) return false;
		-- _group_count;
		bool swapped = false;
		if constexpr(Enable_small_to_large) if(p[u] > p[v]) swap(u, v), swapped = true;
		p[u] += p[v], p[v] = u;
		group[u].splice(group[u].end(), group[v]);
		act(u, v, swapped);
		return true;
	}
	int group_count() const{
		return _group_count;
	}
	const list<int> &group_of(int u){
		return group[root(u)];
	}
	vector<vector<int>> group_up(){
		vector<vector<int>> g(n);
		for(auto i = 0; i < n; ++ i) g[root(i)].push_back(i);
		g.erase(remove_if(g.begin(), g.end(), [&](auto &s){ return s.empty(); }), g.end());
		return g;
	}
	void clear(){
		_group_count = n;
		fill(p.begin(), p.end(), -1);
		for(auto i = 0; i < n; ++ i) group[i] = {i};
	}
	friend ostream &operator<<(ostream &out, disjoint_set dsu){
		auto gs = dsu.group_up();
		out << "{";
		if(!gs.empty()) for(auto i = 0; i < (int)gs.size(); ++ i){
			out << "{";
			for(auto j = 0; j < (int)gs[i].size(); ++ j){
				out << gs[i][j];
				if(j + 1 < (int)gs[i].size()) out << ", ";
			}
			out << "}";
			if(i + 1 < (int)gs.size()) out << ", ";
		}
		return out << "}";
	}
};

template<class T>
struct graph{
	using Weight_t = T;
	struct Edge_t{
		int from, to;
		T cost;
	};
	int n;
	vector<Edge_t> edge;
	vector<vector<int>> adj;
	function<bool(int)> ignore;
	graph(int n = 1): n(n), adj(n){
		assert(n >= 1);
	}
	graph(const vector<vector<int>> &adj, bool undirected = true): n((int)adj.size()), adj(n){
		assert(n >= 1);
		if(undirected){
			for(auto u = 0; u < n; ++ u) for(auto v: adj[u]) if(u < v) link(u, v);
		}
		else for(auto u = 0; u < n; ++ u) for(auto v: adj[u]) orient(u, v);
	}
	graph(const vector<vector<pair<int, T>>> &adj, bool undirected = true): n((int)adj.size()), adj(n){
		assert(n >= 1);
		if(undirected){
			for(auto u = 0; u < n; ++ u) for(auto [v, w]: adj[u]) if(u < v) link(u, v, w);
		}
		else for(auto u = 0; u < n; ++ u) for(auto [v, w]: adj[u]) orient(u, v, w);
	}
	graph(int n, vector<array<int, 2>> &edge, bool undirected = true): n(n), adj(n){
		assert(n >= 1);
		for(auto [u, v]: edge) undirected ? link(u, v) : orient(u, v);
	}
	graph(int n, vector<tuple<int, int, T>> &edge, bool undirected = true): n(n), adj(n){
		assert(n >= 1);
		for(auto [u, v, w]: edge) undirected ? link(u, v, w) : orient(u, v, w);
	}
	int operator()(int u, int id) const{
		#ifdef LOCAL
		assert(0 <= id && id < (int)edge.size());
		assert(edge[id].from == u || edge[id].to == u);
		#endif
		return u ^ edge[id].from ^ edge[id].to;
	}
	int link(int u, int v, T w = {}){ // insert an undirected edge
		int id = (int)edge.size();
		adj[u].push_back(id), adj[v].push_back(id), edge.push_back({u, v, w});
		return id;
	}
	int orient(int u, int v, T w = {}){ // insert a directed edge
		int id = (int)edge.size();
		adj[u].push_back(id), edge.push_back({u, v, w});
		return id;
	}
	void clear(){
		for(auto [u, v, w]: edge){
			adj[u].clear();
			adj[v].clear();
		}
		edge.clear();
		ignore = {};
	}
	graph transposed() const{ // the transpose of the directed graph
		graph res(n);
		for(auto &e: edge) res.orient(e.to, e.from, e.cost);
		res.ignore = ignore;
		return res;
	}
	int degree(int u) const{ // the degree (outdegree if directed) of u (without the ignoration rule)
		return (int)adj[u].size();
	}
	// The adjacency list is sorted for each vertex.
	vector<vector<int>> get_adjacency_list() const{
		vector<vector<int>> res(n);
		for(auto u = 0; u < n; ++ u) for(auto id: adj[u]){
			if(ignore && ignore(id)) continue;
			res[(*this)(u, id)].push_back(u);
		}
		return res;
	}
	void set_ignoration_rule(const function<bool(int)> &f){
		ignore = f;
	}
	void reset_ignoration_rule(){
		ignore = nullptr;
	}
	friend ostream &operator<<(ostream &out, const graph &g){
		for(auto id = 0; id < (int)g.edge.size(); ++ id){
			if(g.ignore && g.ignore(id)) continue;
			auto &e = g.edge[id];
			out << "{" << e.from << ", " << e.to << ", " << e.cost << "}\n";
		}
		return out;
	}
};

// Requires graph
template<class T>
struct bfs_forest{
	int n;
	T base_dist;
	vector<T> dist;
	vector<int> pv;
	vector<int> pe;
	vector<int> order;
	vector<int> pos;
	vector<int> size;
	vector<int> root_of;
	vector<int> root;
	vector<int> depth;
	vector<int> was;
	bfs_forest(T base_dist = 0): base_dist(base_dist){ }
	void init(int n){
		this->n = n;
		pv.assign(n, -1);
		pe.assign(n, -1);
		order.clear();
		pos.assign(n, -1);
		size.assign(n, -1);
		root_of.assign(n, -1);
		root.clear();
		depth.assign(n, -1);
		dist.assign(n, base_dist);
		was.assign(n, -2);
		attempt = -1;
	}
	int attempt;
	vector<int> q;
	// O(# of nodes reachable from src)
	template<class F = plus<>>
	void _bfs(const graph<T> &g, const vector<int> &src, F UT = plus<>()){
		q = src;
		for(auto u: src){
			assert(was[u] != attempt);
			was[u] = attempt;
			depth[u] = 0;
			dist[u] = base_dist;
			root_of[u] = u;
			root.push_back(u);
			pv[u] = -1;
			pe[u] = -1;
		}
		int init_size = (int)order.size();
		for(auto it = 0; it < (int)q.size(); ++ it){
			int u = q[it];
			pos[u] = (int)order.size();
			order.push_back(u);
			size[u] = 1;
			for(auto id: g.adj[u]){
				if(g.ignore && g.ignore(id)) continue;
				int v = g(u, id);
				if(was[v] == attempt) continue;
				was[v] = attempt;
				depth[v] = depth[u] + 1;
				dist[v] = UT(g.edge[id].cost, dist[u]);
				pv[v] = u;
				pe[v] = id;
				root_of[v] = root_of[u];
				q.push_back(v);
			}
		}
		for(auto i = (int)order.size() - 1; i >= init_size; -- i){
			int u = order[i];
			if(~pv[u]) size[pv[u]] += size[u];
		}
		q.clear();
	}
	// O(# of nodes reachable from src)
	template<class F = plus<>>
	void bfs(const graph<T> &g, const vector<int> &src, F UT = plus<>()){
		assert(g.n <= n);
		root.clear(), order.clear();
		for(auto u: src) assert(0 <= u && u < g.n);
		++ attempt;
		_bfs(g, src, UT);
	}
	// O(n + m)
	template<class U, class F = plus<>>
	void bfs_all(const graph<U> &g, F UT = plus<>()){
		assert(g.n <= n);
		root.clear(), order.clear();
		++ attempt;
		for(auto u = 0; u < g.n; ++ u) if(was[u] != attempt) _bfs(g, {u}, UT);
	}
	// Check if u is visited during the last bfs-like call.
	bool visited(int u) const{
		assert(0 <= u && u < n);
		return was[u] == attempt;
	}
	vector<int> get_path(int u, int v) const{
		assert(visited(u) && visited(v) && root_of[u] == root_of[v]);
		vector<int> left, right;
		while(u != v){
			if(depth[u] >= depth[v]){
				left.push_back(u);
				u = pv[u];
			}
			else{
				right.push_back(v);
				v = pv[v];
			}
		}
		left.push_back(u);
		left.insert(left.end(), right.rbegin(), right.rend());
		return left;
	}
};

int main(){
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(ios::badbit | ios::failbit);
	int n, m, from, to, len;
	cin >> n >> m >> from >> to >> len, -- from, -- to;
	auto _f = [&](string s)->void{
		cout << s << endl;
		exit(0);
	};
	auto yes = [&]()->void{
		_f("Yes");
	};
	auto no = [&]()->void{
		_f("No");
	};
	auto unknown = [&]()->void{
		_f("Unknown");
	};
	disjoint_set dsu(n << 1);
	graph<int> g(n);
	for(auto i = 0; i < m; ++ i){
		int u, v;
		cin >> u >> v, -- u, -- v;
		dsu.merge(u << 1, v << 1 | 1);
		dsu.merge(u << 1 | 1, v << 1);
		g.link(u, v);
	}
	bfs_forest<int> bf;
	bf.init(n);
	bf.bfs(g, {from});
	if(from == to){
		if(len & 1){
			no();
		}
		bf.size[from] >= 2 ? yes() : n == 1 ? no() : unknown();
	}
	if(n == 2){
		if(~len & 1){
			no();
		}
		bf.size[from] >= 2 ? yes() : unknown();
	}
	if(dsu.share(from << 1, to << 1)){
		if(len & 1){
			no();
		}
		bf.depth[to] == len || bf.depth[to] < len && bf.size[from] >= 2 ? yes() : unknown();
	}
	else if(dsu.share(from << 1, to << 1 | 1)){
		if(~len & 1){
			no();
		}
		bf.depth[to] == len || bf.depth[to] < len && bf.size[from] >= 2 ? yes() : unknown();
	}
	else{
		unknown();
	}
	return 0;
}

/*

*/