#include<iostream>
#include<cmath> 
using namespace std;
int n,m,s,f[500005][19],deep[500005],h[1000005],u[500005];
struct tu{
   int t;
   int n;
}b[1000005];
void in(int i,int x,int y){
	b[i].t=y,b[i].n=h[x],h[x]=i;
}
void go(int c,int d){
	u[c]=1,deep[c]=d;
	for(int e=h[c];e;e=b[e].n) if(!u[b[e].t]){
		f[b[e].t][0]=c;
		go(b[e].t,d+1);
	}
	return;
}
void build(){
	for(int i=1;i<=n;i++)
		for(int j=1;j<=log2(deep[i]-1);j++)
			f[i][j]=f[f[i][j-1]][j-1];
}
int LCA(int x,int y){
	if(deep[x]<deep[y])	swap(x,y);
	int c=deep[x]-deep[y];
	while(c>0){
		int j=(int)(log2(c));
		x=f[x][j],c-=pow(2,j);
	}
	if(x==y) return x;
	int j=(int)(log2(deep[x]-1));
	//cout<<x<<" "<<y<<" "<<j<<" "<<f[x][j]<<" "<<f[y][j]<<endl;
	while(f[x][j]!=f[y][j]){
		x=f[x][j],y=f[y][j];
		if(x==s) return x;
		j=(int)(log2(deep[x]-1));
	}
	while(x!=y) x=f[x][0],y=f[y][0];
	return x;
}
int main(){
	cin>>n>>m>>s;
	for(int i=1;i<n;i++){
		int x,y;
		cin>>x>>y;
		in(i*2-1,x,y);
		in(i*2,y,x);
	}
	go(s,1);
	build();
	for(int i=1;i<=m;i++){
		int x,y;
		cin>>x>>y;
		cout<<LCA(x,y)<<endl;
	}
	return 0;
} 

记录