#include <bits/stdc++.h>
using namespace std;
static void DFS(int curr,int prev,vector<int>& res,bool maximum,const vector<vector<int>>& edges) {
static int time = 0;
if (!maximum)
res[curr] = ++time;
for (int edge : edges[curr]) if (edge != prev) DFS(edge,curr,res,!maximum,edges);
if (maximum)
res[curr] = ++time;
}
vector<int> label(int n, int, vector<int> u, vector<int> v) {
vector<vector<int>> edges(n);
for (int i = 0; i < n-1; i++) {
edges[u[i]].emplace_back(v[i]);
edges[v[i]].emplace_back(u[i]);
}
vector<int> res(n);
DFS(0,0,res,false,edges);
return res;
}
int find_next_station(int s, int t, vector<int> c) {
if (s < c[0]) {
if (t >= c.back() || t < s)
return c.back();
return *ranges::upper_bound(c,t-1);
}
if (t > s)
return c[0];
return *--ranges::upper_bound(c,t);
}
#if 0
int main() {
int n;
cin >> n;
vector<int> edge1(n-1),edge2(n-1);
for (int i = 0; i < n-1; i++) {
edge1[i] = i;
edge2[i] = i + 1;
}
auto labels = label(n,0,edge1,edge2);
int beginVal,endVal;
cin >> beginVal >> endVal;
map<int,int> mapping;
for (int i = 0; i < n; i++)
mapping[labels[i]] = i;
int currentIndex = beginVal;
while (currentIndex != endVal) {
vector<int> values;
if (mapping[currentIndex] != 0)
values.emplace_back(labels[mapping[currentIndex]-1]);
if (mapping[currentIndex] != n-1)
values.emplace_back(labels[mapping[currentIndex]+1]);
ranges::sort(values);
currentIndex = find_next_station(currentIndex,endVal,values);
}
}
#endif
