#include <bits/stdc++.h>
using namespace std;

const int N = 5e5+5;
int n, m, s,f [N][22], sh[N];
vector<int> e[N];
void dfs(int x,int fa){
	sh[x] = sh[fa] + 1;
	f[x][0] = fa;
	for(int i = 1;(1 << i) <= sh[x];i++){
		f[x][i] = f[f[x][i - 1]][i - 1];
	}
	for(int i = 0;i < e[x].size();i++){//auto i: e[x]
		int v = e[x][i];
		if(v != fa){
			dfs(v, x);
		}
	}

}
int lca(int x, int y){
	if(sh[y] > sh[x]) swap(x,y);
	for(int k = 19;k >= 0;k--) if(sh[f[x][k]]>=sh[y]) x = f[x][k];
	if(x==y) return x;
	for(int k = 19;k >= 0;k--) if(f[x][k] != f[y][k]) x = f[x][k],y = f[y][k];
	return f[x][0];
}

int main()
{	
	cin>>n>>m>>s;
	for(int i  = 1;i <= n - 1;i++){
		int x, y;
		cin>>x>>y;
		e[x].push_back(y);
		e[y].push_back(x);
	}
	
	dfs(s,0);
	
	for(int i = 1;i <= m;i++){
		int a, b;
		cin>>a>>b;
		cout<<lca(a,b)<<endl;
	}
    return 0;
}

#include <bits/stdc++.h>
using namespace std;

const int N = 5e5+10;
int n, m, s, f[N][22], sh[N];
vector<int> e[N];
void dfs(int x, int fa){
	f[x][0] = fa;
	sh[x] = sh[fa] + 1;
	for(int i = 1;(1 << i )<= sh[x];i++){
		f[x][i] = f[f[x][i - 1]][i - 1];
	}
	for(int i = 0;i < e[x].size();i++){
		int v = e[x][i];
		if(v != fa){
			dfs(v,x);
		}
	}
}

int lca(int x, int y){
	if(sh[x] < sh[y]) swap(x, y);
	for(int i = 19;i >= 0;i--){
		if(sh[y] <= sh[f[x][i]]){
			x = f[x][i];
		}
	}
	if(x == y) return x;
	for(int i = 19;i >= 0;i--){
		if(f[y][i] != f[x][i]){
			x = f[x][i],y = f[y][i];
		}
	} 
	return f[x][0];
}

int main()
{	
	cin>>n>>m>>s;
	for(int i  = 1;i <= n - 1;i++){
		int x, y;
		cin>>x>>y;
		e[x].push_back(y);
		e[y].push_back(x);
	}
	
	dfs(s,0);
	
	int a, b;
	for(int i = 1;i <= m;i++){
		cin>>a>>b;
		cout<<lca(a,b)<<endl;
	}
    return 0;
}