#include<bits/stdc++.h>

const int N = 5e5+10;
using namespace std;

vector<int> a[N];
int n,m,s,x,y,cnt;
int d[N],anc[N][20];

inline void add(int u,int v)
{
	a[u].push_back(v);
	a[v].push_back(u);
}

int dfs(int u,int fa)
{
	for(int i = 0;i < a[u].size();i++)
	{
		int v = a[u][i];
		if(v == fa)
     	{
			continue;
		}
		d[v] = d[u] + 1;
		anc[v][0] = u;
		dfs(v,u);
	} 
}
void init()
                                      {
	for(int j=1;j<=18;j++)
  {
		for(int i=1;i<=n;i++){
			anc[i][j] = anc[anc[i][j-1]][j-1];
		}
	} 
}
                              
int Lca(int u,int v){
	if(d[u] < d[v])
  {
		swap(u,v);
	}
	for(int i=18;i>=0;i--)
  {
		if(d[anc[u][i]] >= d[v]){
			u = anc[u][i];
		}
	}
	if(u == v){
		return u;
	}
	for(int i=18;i>=0;i--){
		if(anc[u][i] != anc[v][i]){
			u = anc[u][i];
			v = anc[v][i];
		}
	}
	return anc[u][0];
}
int main(){
//	freopen("P3379_1.in","r",stdin);
	scanf("%d%d%d",&n,&m,&s);
//	printf("%d\n",n);
	for(int i=1;i<=n-1;i++){
		scanf("%d%d",&x,&y);
		add(x,y);
	}
	d[s] = 1;
//	printf("!");
	dfs(s,0);
	init();
	while(m--){
		scanf("%d%d",&x,&y);
		printf("%d\n",Lca(x,y));
	}
}