#include <bits/stdc++.h>
#include "highway.h"
using namespace std;
long long ask(const std::vector<int> &w);
void answer(int s, int t);
int search(int n, int D) {
vector<int>A(n,1);
int l = 0, r = n-1;
int ans = -1;
while(l <= r) {
//cout << l << " " << r << "\n";
if(l == r) {
return l;
}
bool T = (r - l == 1);
int mid = (l+r)/2;
for(int i = mid+1 ; i <= r ; i++)
A[i] = 0;
if(ask(A) != D) {
ans = l;
r = mid;
} else {
for(int i = l ; i <= mid ; i++)
A[i] = 0;
for(int i = mid+1 ; i <= r ; i++)
A[i] = 1;
l = mid+1;
}
}
return ans;
}
const int mxN = (int)9e4 + 5;
map<pair<int,int>,int>mp;
vector<int>adj[mxN];
vector<int>edges;
vector<int>go;
set<int>nC;
void dfs(int u, int d, int e = -1) {
if(d == 1) {
for(auto z : adj[u]) if(z != e && !nC.count(z)) {
edges.push_back(mp[{u,z}]);
go.push_back(z);
}
return;
}
for(auto z : adj[u]) if(z != e) {
dfs(z, d-1, u);
}
}
bool delDFS(int u, int S, int e = -1) {
if(u == S) {
nC.insert(u);
return 1;
}
bool ok = 0;
for(auto z : adj[u]) if(z != e) {
ok |= delDFS(z, S, u);
}
if(ok)
nC.insert(u);
return ok;
}
int C = 1;
void check() {
// cout << "Check " << C++ << "\n";
}
int conSearch(int m, int dist) {
const int n = (int)edges.size();
vector<int>A(m,0);
int l = 0, r = n-1;
int ans = -1;
while(l <= r) {
if(l == r)
return go[l];
int mid = (l+r)/2;
for(auto &z : A)
z = 0;
for(int i = 0 ; i <= mid ; i++)
A[edges[i]] = 1;
if(ask(A) != dist) {
r = mid;
ans = go[mid];
} else l = mid+1;
}
return ans;
}
void find_pair(int n, vector<int>u, vector<int>v, int a, int b) {
const int m = (int)u.size();
for(int i = 0 ; i < m ; i++) {
adj[u[i]].push_back(v[i]);
adj[v[i]].push_back(u[i]);
}
vector<int>A(m,0);
for(int i = 0 ; i < m ; i++)
mp[{u[i],v[i]}] = mp[{v[i],u[i]}] = i;
int dist = ask(A) / a;
int id = search(m, dist * a);
int f = u[id], s = v[id];
int l = 0, r = dist;
check();
// cout << f << " " << s << "\n";
int S,T;
int D;
while(l <= r) {
edges.clear();
go.clear();
int mid = (l+r)/2;
dfs(f,mid);
for(auto &z : A)
z = 0;
for(auto z : edges)
A[z] = 1;
check();
/*cout << l << " " << r << "\n";
for(auto z : edges)
cout << z << " ";
cout << "\n";
*/
if(ask(A) != dist*a) {
S = conSearch(m, dist*a);
l = mid+1;
D = mid;
} else r = mid-1;
//cout << "S " << S << "\n";
}
if(S == -1)
S = f;
delDFS(f, S);
check();
/*for(auto it = nC.begin() ; it != nC.end() ; it++)
cout << *it << " ";
cout << "\n";
*/
edges.clear();
go.clear();
dfs(s, dist - D + 1);
/*cout << "Final ";
for(auto z : edges)
cout << z << " ";
cout << "\n";
*/
T = conSearch(m, dist*a);
check();
//cout << S << " " << T << "\n";
answer(S,T);
}
/*
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <utility>
#include <vector>
namespace {
constexpr int MAX_NUM_CALLS = 100;
constexpr long long INF = 1LL << 61;
int N, M, A, B, S, T;
std::vector<int> U, V;
std::vector<std::vector<std::pair<int, int>>> graph;
bool answered, wrong_pair;
int num_calls;
int read_int() {
int x;
if (scanf("%d", &x) != 1) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}
return x;
}
void wrong_answer(const char *MSG) {
printf("Wrong Answer: %s\n", MSG);
exit(0);
}
} // namespace
long long ask(const std::vector<int> &w) {
if (++num_calls > MAX_NUM_CALLS) {
wrong_answer("more than 100 calls to ask");
}
if (w.size() != (size_t)M) {
wrong_answer("w is invalid");
}
for (size_t i = 0; i < w.size(); ++i) {
if (!(w[i] == 0 || w[i] == 1)) {
wrong_answer("w is invalid");
}
}
std::vector<bool> visited(N, false);
std::vector<long long> current_dist(N, INF);
std::queue<int> qa, qb;
qa.push(S);
current_dist[S] = 0;
while (!qa.empty() || !qb.empty()) {
int v;
if (qb.empty() ||
(!qa.empty() && current_dist[qa.front()] <= current_dist[qb.front()])) {
v = qa.front();
qa.pop();
} else {
v = qb.front();
qb.pop();
}
if (visited[v]) {
continue;
}
visited[v] = true;
long long d = current_dist[v];
if (v == T) {
return d;
}
for (auto e : graph[v]) {
int vv = e.first;
int ei = e.second;
if (!visited[vv]) {
if (w[ei] == 0) {
if (current_dist[vv] > d + A) {
current_dist[vv] = d + A;
qa.push(vv);
}
} else {
if (current_dist[vv] > d + B) {
current_dist[vv] = d + B;
qb.push(vv);
}
}
}
}
}
return -1;
}
void answer(int s, int t) {
if (answered) {
wrong_answer("answered not exactly once");
}
if (!((s == S && t == T) || (s == T && t == S))) {
wrong_pair = true;
}
answered = true;
}
int main() {
N = read_int();
M = read_int();
A = read_int();
B = read_int();
S = read_int();
T = read_int();
U.resize(M);
V.resize(M);
graph.assign(N, std::vector<std::pair<int, int>>());
for (int i = 0; i < M; ++i) {
U[i] = read_int();
V[i] = read_int();
graph[U[i]].push_back({V[i], i});
graph[V[i]].push_back({U[i], i});
}
answered = false;
wrong_pair = false;
num_calls = 0;
find_pair(N, U, V, A, B);
if (!answered) {
wrong_answer("answered not exactly once");
}
if (wrong_pair) {
wrong_answer("{s, t} is wrong");
}
printf("Accepted: %d\n", num_calls);
return 0;
}
*/
