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

int n, m, s, dep[500005], fa[500005];
vector < int > e[500005];
bool vis[500005];

void getdep(int x, int f)
{
	if(vis[x])return;
	vis[x] = 1;
	fa[x] = f;
	dep[x] = dep[f] + 1;
	for(auto i : e[x])
		getdep(i, x);
}

int LCA(int x, int y)
{
	while(x != y)
	{
		if(dep[x] >= dep[y])
			x = fa[x];
		else
			y = fa[y];
	}
	return x;
}

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);
	}
	
	dep[0] = -1;
	getdep(s, 0);
	
	for(int i = 1; i <= m; i++)
	{
		int x, y;
		cin >> x >> y;
		cout << LCA(x, y) << endl;
	}
	
	return 0;
}