#include<iostream>
#include<cstdio>
#include<vector>
#include<cmath>
using namespace std;
const int N = 5e5+5;
struct node{
	int deep;
	int num;
}minn[N][20];
node min_deep(node a,node b){
	if(a.deep < b.deep){
		return a;
	}
	else{
		return b;
	}
}
vector<int> a[N];
vector<node> b;
int d[N],c[N],cnt = 0;
void deep(int now,int fa){
	d[now] = d[fa] + 1;
	for(int i=0;i<a[now].size();i++){
		if(a[now][i] != fa){
			deep(a[now][i],now);
		}
	}
}
void dfs(int now,int fa){
	cnt ++;
	c[now] = cnt;
	b.push_back({d[now],now});
	for(int i=0;i<a[now].size();i++){
		if(a[now][i] != fa){
			dfs(a[now][i],now);
		}
	}
}
int query(int l,int r){
	int k = log2(r-l+1);
	return min_deep(minn[l][k],minn[r-(1<<k)+1][k]).num;
}
int main(){
	int n,m,s,x,y;
	scanf("%d%d%d",&n,&m,&s);
	for(int i=1;i<=n-1;i++){
		scanf("%d%d",&x,&y);
		a[x].push_back(y);
		a[y].push_back(x);
	}
	deep(s,0);//初始化深度; 
	dfs(s,0);//求dfs序; 
	for(int i=1;i<=n;i++){
		minn[i][0] = b[i];
	}
	for(int j=1;j<=18;j++){
		for(int i=1;i+(1<<j)-1 <= n;i++){
			minn[i][j] = min_deep(minn[i][j-1],minn[i+(1<<(j-1))][j-1]);
		}
	}
	for(int i=1;i<=m;i++){
		scanf("%d%d",&x,&y);//查询区间[c[x],c[y]]内的最小深度所对应的编号; 
		printf("%d\n",query(x,y));
	}
}