#include <iostream>
#include <vector>
using namespace std;
const int N=500010;
vector <int> e[N];
int fa[N][20],dep[N];
void dfs(int u,int father){
	dep[u]=dep[father]+1;
	fa[u][0]=father;
	for (int i=1;i<=19;i++){
		fa[u][i]=fa[fa[u][i-1]][i-1];
	}
	for (vector<int>::iterator i=e[u].begin();i<e[u].end();i++){
		int v = *i;
		if (v!=father){
			dfs(v,u);
		}
	}
}
int lca(int u,int v){
	if (dep[u]<dep[v])
		swap(u,v);
	for (int i=19;i>=0;i--){
		if (dep[fa[u][i]]>=dep[v]){
			u=fa[u][i];
		}
	}
	if (u==v)
		return u;
	for (int i=19;i>=0;i--){
		if (fa[u][i]!=fa[v][i]){
			u=fa[u][i];
			v=fa[v][i];
		}
	}
	return fa[u][0];
}
int main(){
	int n,m,s;
	cin>>n>>m>>s;
	for (int i=1;i<n;i++){
		int x,y;
		cin>>x>>y;
		e[x].push_back(y);
	}
	
	dfs(s,0);
	
	for (int i=1;i<=m;i++){
		int x,y;
		cin>>x>>y;
		cout<<lca(x,y)<<endl;
	}
	return 0;
}