#include <iostream>
#define MAXN 500010
using namespace std;
int n, m, s;
int k;
int head[MAXN], d[MAXN], f[MAXN][21];
struct node
{
	int v, nxt;
}e[MAXN<<1];
void add(int u, int v)
{
	e[++k].v = v;
	e[k].nxt = head[u];
	head[u] = k;
}

void init(int u, int fa)
{
	d[u] = d[fa] + 1;
	for (int i = 0; i<=19; i++)
	{
		f[u][i+1] = f[f[u][i]][i];
		
	}
	for (int i = head[u]; i; i = e[i].nxt)
	{
		int v = e[i].v;
		if (v == fa) continue;
		f[v][0] = u;
		init(v, u);
	}
}

int lca(int x, int y)
{
	if (d[x] < d[y]) swap(x, y);
	for (int i = 20; i >= 0; i--)
	{
		if (d[f[x][i]] >= d[y]) x = f[x][i];
		if (x == y) return x;
	}
	for (int i = 20; i >= 0; i--)
	{
		if (f[x][i] != f[y][i])
		{
			x = f[x][i];
			y = f[y][i];
		}
	}
	return f[x][0];
}

int main()
{
	cin >> n >> m >> s;
	for (int i = 1; i < n; i++)
	{
		int a=0, b=0;
		cin >> a, b;
		add(a, b);
		add(b, a);
	}
	init(s, 0);
	for (int i = 1; i <= m; i++)
	{
		int a=0, b=0;
		cin >> a >> b;
		cout << lca(a, b)<<endl;
	}
	return 0;
}