#include <bits/stdc++.h>
using namespace std;
inline int read()
{
    int x = 0, f = 1;char ch = getchar();
    while (ch < '0' || ch > '9') {if (ch == '-') f = -1;ch = getchar();}
    while (ch >= '0' && ch <= '9') x= x * 10 + ch - '0', ch = getchar();
    return x * f;
}
const int N = 500000 + 5, LogN = 20;
int n, m, s;
vector<int> v[N];
int fa[N][LogN], dep[N], Log[N];
void Readin() {
	n = read(), m = read(), s = read();
	for (int i = 1, x, y; i < n; i++) {
		x = read(), y = read();
		v[x].push_back(y);
		v[y].push_back(x);
	}
	return;
}
void init() {
	for (int i = 1; i <= n; i++)
		Log[i] = (int)log2(1.000 * i);
	return;
}
void dfs(int x, int fat) {
	fa[x][0] = fat;
	dep[x] = dep[fat] + 1;
	for (int i = 1; i <= Log[dep[x]]; i++) {
		fa[x][i] = fa[fa[x][i - 1]][i - 1];
	}
	for (int i = 0; i < (int)v[x].size(); i++) {
		int u = v[x][i];
		if (u != fat)
			dfs(u, x);
	}
	return;
}
int LCA(int a, int b) {
	if (dep[a] < dep[b]) swap(a, b);
	if (dep[a] > dep[b]) a = fa[a][Log[dep[a] - dep[b]]];
	if (a == b) return a;
	for (int i = Log[dep[a]]; i >= 0; i--) {
		if (fa[a][i] != fa[b][i]) a = fa[a][i], b = fa[b][i];
	}
	return fa[a][0];
}
int main() {
	Readin();
	init();
	dep[0] = 0;
	dfs(s, 0);
	int a, b;
	while (m--) {
		a = read(), b = read();
		cout << LCA(a, b) << '\n';
	}
	return 0;
}