#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;

int f[500001][20];
int dep[500001];
int maxL;
const int N = 500001;

struct edge
{
    int to, nxt; // w是边长
}e[N*2];
int cnt, head[N];
void add(int x, int y)
{
    e[++cnt] = (edge){y, head[x]};
    head[x] = cnt;
}

void dfs(int x, int fa)
{
	dep[x] = dep[fa]+1;
	f[x][0] = fa;
	for(int i = 1;(1<<i) <= dep[x];i++)
	{
		f[x][i] = f[f[x][i-1]][i-1];
		maxL = max(i, maxL);
	}
	for(int i = head[x];i;i = e[i].nxt)
    {
        int y = e[i].to;
        if(y == fa) continue;
        dfs(y,x);
    }
}

int lca(int x, int y)
{
	if(dep[x] < dep[y]) swap(x,y);
	for(int i = maxL;i >= 0;i--)
		if(dep[x] - dep[y] >= (1<<i))
			x = f[x][i];
	if(x == y) return x;
	// 深度更大的点向上走，直到两点深度相同
	
	for(int i = maxL;i >= 0;i--)
		if(f[x][i] != f[y][i])
			 x = f[x][i], y = f[y][i];
	// 两点同时向上走，走到重合时停止
	
	return f[x][0];
	// 返回f[x][0];
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n, m, s;
	cin >> n >> m >> s;
	for(int i = 1;i < n;i++)
	{
		int x, y;
		cin >> x >> y;
		add(x, y);
		add(y, x);
	}
	dfs(s,s);
	for(int i = 1;i <= m;i++)
	{
		int a, b;
		cin >> a >> b;
		cout << lca(a, b) << "\n";
	}
	return 0;
}