#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 5;
vector<int> g[maxn]; 
int n, m, s, dep[maxn], fa[maxn][21];

void dfs(int u, int p) {
	dep[u] = dep[p] + 1;
	fa[u][0] = p;
	for (auto v : g[u])
		if (v != p)
			dfs(v, u);
}

int lca(int u, int v) {
	if (dep[u] < dep[v])
		swap(u, v);
	for (int i = 20; i >= 0; i--)
		if (dep[fa[u][i]] >= dep[v])
			u = fa[u][i];
	assert(dep[u] == dep[v]);	// 断言 
	if (u == v) return u;
	for (int i = 20; i >= 0; i--)
		if (fa[u][i] != fa[v][i])
			u = fa[u][i], v = fa[v][i];
	assert(fa[u][0] == fa[v][0]);
	return fa[u][0];
}

int main() {
	scanf("%d%d%d", &n, &m, &s);
	for (int i = 1; i < n; i++) {
		int u, v;
		scanf("%d%d", &u, &v);
		g[u].push_back(v);
		g[v].push_back(u);
	}
	dfs(s, 0);
	for (int i = 1; i <= 20; i++)
		for (int u = 1; u <= n; u++)
			fa[u][i] = fa[fa[u][i-1]][i-1];
	while (m--) {
		int u, v;
		scanf("%d%d", &u, &v);
		printf("%d\n", lca(u, v));
	}
	return 0;
}