#include "Annalib.h"
#include<vector>
#include<queue>
#include<cstring>

using namespace std;

int dis[100005], h[100005], en;
queue<int> q;
struct edge {
	int v, next;
} e[200005];
void add(int u, int v) {
	e[en] = (edge){v, h[u]}; h[u] = en++;
}

void Anna(int K, int N, int T, int A[], int B[]) {
	memset(dis, 0x3f, sizeof(dis));
	memset(h, 0xff, sizeof(h));
	en = 0;
	for(int i = 0; i < N - 1; i++) add(A[i], B[i]), add(B[i], A[i]);
	q.push(T);
	while(!q.empty()) {
		int r = q.front(); q.pop();
		Flag(r, (dis[r] / 2) % 2);
		for(int j = h[r]; ~j; j = e[j].next) {
			int v = e[j].v;
			if(dis[v] > 2) {
				if(v < r) dis[v] = dis[r];
				else dis[v] = 1 - dis[r];
			}
		}
	}
}

#include "Brunolib.h"

void Bruno(int K, int S, int F, int L, int P[], int Q[]) {
	for(int i =  0; i < L; i++) {
		if((Q[i] == F) ^ (S > P[i])) {
			Answer(P[i]);
			return ;
		}
	}
	Answer(S);
}