#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
struct zzz {
    int t, nex;
}e[500010 << 1]; int head[500010], tot;
void add(int x, int y) {
	e[++tot].t = y;
	e[tot].nex = head[x];
	head[x] = tot;
}
int depth[500001], fa[500001][22], lg[500001];
void dfs(int now, int fath) {
	fa[now][0] = fath; depth[now] = depth[fath] + 1;
	for(int i = 1; i <= lg[depth[now]]; ++i)
		fa[now][i] = fa[fa[now][i-1]][i-1];
	for(int i = head[now]; i; i = e[i].nex)
		if(e[i].t != fath) dfs(e[i].t, now);
}
int LCA(int x, int y) {
	if(depth[x] < depth[y]) swap(x, y);
	while(depth[x] > depth[y])
		x = fa[x][lg[depth[x]-depth[y]] - 1];
	if(x == y) return x;
	for(int k = lg[depth[x]] - 1; k >= 0; --k)
		if(fa[x][k] != fa[y][k])
			x = fa[x][k], y = fa[y][k];
	return fa[x][0];
}
int main() {
	int n, m, s; scanf("%d%d%d", &n, &m, &s);
	for(int i = 1; i <= n-1; ++i) {
		int x, y; scanf("%d%d", &x, &y);
		add(x, y); add(y, x);
	}
	for(int i = 1; i <= n; ++i)
		lg[i] = lg[i-1] + (1 << lg[i-1] == i);
	dfs(s, 0);
	for(int i = 1; i <= m; ++i) {
		int x, y; scanf("%d%d",&x, &y);
		printf("%d\n", LCA(x, y));
	}
	return 0;
}