$Code$

#include<bits/stdc++.h>
using namespace std;

const int MAXN=500000+5;
const int MAXM=500000+5;

int head[MAXN];
int father[MAXN];
bool visited[MAXM];
int bianshu;

struct edge
{
	int v,next;
}g[2*MAXM];

void addedge(int u,int v)
{
	g[++bianshu].next=head[u];
	g[bianshu].v=v;
	head[u]=bianshu;
	return;
}

queue <int> q;
int s;
void bfs()
{
	q.push(s);
	while(!q.empty())
	{
		int ppp=q.front();
		q.pop();
		for(int i=head[ppp];i;i=g[i].next)
		{
			if(!visited[g[i].v])
			{
				visited[g[i].v]=true;
				father[g[i].v]=ppp;
				q.push(g[i].v);
			}
		}
	}
	
}

int path1[MAXN];
int path2[MAXN];
int cntp1,cntp2;
int ans;
int main()
{
	int n,q;
	int uu,vv;
	int a,b;
	int LCA,a1,a2;
	scanf("%d%d%d",&n,&q,&s);
	for(int i=1;i<=n-1;++i)
	{
		scanf("%d%d",&uu,&vv);
		addedge(uu,vv);
		addedge(vv,uu);
	}
	father[s]=s;
	visited[s]=true;
	bfs();
	for(int i=1;i<=q;++i)
	{
		scanf("%d%d",&a,&b);
		for(int j=a;j!=s;j=father[j])
		{
			path1[++cntp1]=j;
		}
		path1[++cntp1]=s;
		for(int j=b;j!=s;j=father[j])
		{
			path2[++cntp2]=j;
		}
		path2[++cntp2]=s;
		while(path1[cntp1--]==path2[cntp2--])
		{
			ans=path1[cntp1+1];
		}
		printf("%d\n",ans);
		memset(path1,0,sizeof(path1));
		memset(path2,0,sizeof(path2));
		cntp1=0;
		cntp2=0;
		ans=0;
	}
	return 0;
}