#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
int n,m,s,x,y,fa[500005][22],depth[500005],lg[500005],ans;
vector <int> edge[500005];
void dfs(int x,int fax){
	fa[x][0]=fax;
	depth[x]=depth[fax]+1;
	for(int i=1;i<=lg[depth[x]];i++){
		fa[x][i]=fa[fa[x][i-1]][i-1];
	}
	for(int i=0;i<edge[x].size();i++){
		if(edge[x][i]!=fax){
			dfs(edge[x][i],x);
		}
	}
}
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]]];
	}
	if(x==y){
		return x;
	}
	for(int k=lg[depth[x]];k>=0;k--){
		if(fa[x][k]!=fa[y][k]){
			x=fa[x][k];
			y=fa[y][k];
		}
	}
	return fa[x][0];
}
int main(){
	scanf("%d %d %d",&n,&m,&s);
	for(int i=1;i<=n-1;i++){
		scanf("%d %d",&x,&y);
		edge[x].push_back(y);
		edge[y].push_back(x);
	}
	for(int i=1;i<=n;i++){
		lg[i]=lg[i/2]+1;
	}
	dfs(s,s);
	for(int i=1;i<=m;i++){
		scanf("%d %d",&x,&y);
		ans=lca(x,y);
		printf("%d\n",ans);
	}
	return 0;
}