#include<bits/stdc++.h>
using namespace std;
int n, m, s;
int fa[500007][40];
int dep[500007];
vector<int>son[500007];
void add(int x, int y) {
	son[x].push_back(y);
	son[y].push_back(x);
}
void dfs(int u, int f, int d) {
	fa[u][0] = f;
	dep[u] = d;
	int v;
	for (int i = 0; i < son[u].size(); i++) {
		v = son[u][i];
		if (f == v)continue;
		dfs(v, u, d + 1);
	}
}
int lca(int x, int y) {
	if (dep[x] < dep[y])swap(x, y);
	for (int i = 18; i >= 0; i--) {
		if (dep[fa[x][i]] >= dep[y]) {
			x = fa[x][i];
		}
	}
	if (x == y)return x;
	for (int i = 18; i >= 0; i--) {
		if (fa[x][i] != fa[y][i]) {
			x = fa[x][i];
			y = fa[y][i];
		}
	}
	if (x == s) {
		return s;
	}
	return fa[x][0];
}
int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m >> s;
	for (int i = 1; i < n; i++) {
		int x, y;
		cin >> x >> y;
		add(x, y);
	}
	dfs(s,0,1);
	while (m--) {
		int x, y;
		cin >> x >> y;
		cout << lca(x, y) << '\n';
	}
	return 0;
}