#include<stdio.h>
#include<algorithm>
#include<vector>
using namespace std;
int n, m, s;

int depth[500005], fa[500005][25];
int lg[500005];
vector<int> g[500005];

void init_lg()
{
	for (int i = 1; i <= n; i++)
	{
		lg[i] = lg[i - 1] + (1 << lg[i - 1] == i);
	}
}

void dfs(int now, int fath)
{
	fa[now][0] = fath; depth[now] = depth[fath] + 1;
	for (int i = 1; i <= lg[depth[now]] - 1; i++)
		fa[now][i] = fa[fa[now][i - 1]][i - 1];
	int size = g[now].size();
	for (int i = 0; i < size; i++)
		dfs(g[now][i], 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];
	//保证跳到同一高度 接下来一起跳
	if (x == y) return x;
	for (int i = lg[depth[x]] - 1; i >= 0; i--)
	{
		if (fa[x][i] != fa[y][i])
		{
			x = fa[x][i];
			y = fa[y][i];
		}
	}
	return fa[x][0];
}

int main()
{
	scanf("%d %d %d", &n, &m, &s);
	int from, to;
	for (int i = 0; i < n - 1; i++)
	{
		scanf("%d %d", &from, &to);
		g[to].push_back(from);
	}
	init_lg();
	dfs(s, 0);
	int a, b;
	for (int i = 1; i <= m; i++)
	{
		scanf("%d %d", &a, &b);
		printf("%d\n", lca(a, b));
	}
	return 0;
}