#include<bits/stdc++.h>
using namespace std;
int in(){
	int ans=0,f=1;
	char c=getchar();
	for(;!isdigit(c);c=getchar()) if(c=='-') f=-1;
	for(;isdigit(c);c=getchar()) ans=ans*10+c-'0';
	return ans*f;
}
void out(int x){
	if(x<0){
		putchar('-');
		x=-x;
	}
	if(x>=10) out(x/10);
	putchar(x%10+'0');
}
int n,q,fir[500010],ne[1000010],en[1000010],f[1000010][15],fa[500010],d[500010],cnt;
void add(int u,int v){
	cnt++;
	ne[cnt]=fir[u];
	en[cnt]=v;
	fir[u]=cnt;
}
void dfs(int u,int deep){
	d[u]=deep;
	int t=fir[u];
	while(t){
		int v=en[t];
		if(fa[u]!=v){
			fa[v]=u;
			dfs(v,deep+1);
		}
		t=ne[t];
	}
}
void build(){
	for(int i=1;i<=n;i++) f[i][0]=fa[i];
	for(int j=1;j<=log2(n);j++){
		for(int i=1;i<=n;i++){
			if(d[i]>(1<<j)) f[i][j]=f[f[i][j-1]][j-1];
		}
	}
}
int lca(int u,int v){
	if(d[u]>d[v]) swap(u,v);
	int k=log2(d[v]-d[u]);
	for(int j=k;j>=0;j--) if(d[v]-(1<<j)>=d[u]) v=f[v][j];
	if(u==v) return u;
	int m=log2(d[u]);
	for(int j=m;j>=0;j--){
		if(f[u][j]!=f[v][j]){
			u=f[u][j],v=f[v][j];
		}
	}
	return fa[u];
}
int main(){
//	freopen("spot.in","r",stdin);
//	freopen("spot.out","w",stdout);
	n=in();
	q=in();
	int root=in();
	int u,v;
	for(int i=1;i<n;i++){
		u=in();v=in();
		add(u,v);
		add(v,u);
	}
	dfs(root,1);
	build();
	while(q--){
		u=in();v=in();
		int t=lca(u,v);
		out(t);
		putchar('\n');
	}
	return 0;
}