# include <bits/stdc++.h>
using namespace std;
const int size=500005;
int f[size][25],d[size];//,dist[size];
int ver[size*2],Next[size*2],edge[size*2],head[size];
int T,n,m,tot,t,s;
queue<int> q;
void add(int x,int y,int z)
{
	ver[++tot]=y;
	edge[tot]=z;
	Next[tot]=head[x];
	head[x]=tot;
}
void bfs()
{
	q.push(T);
	d[T]=1;
	while(q.size())
	{
		int x=q.front();q.pop();
		for (int i=head[x];i;i=Next[i])
		{
			int y=ver[i];
			if (d[y]) continue;
			d[y]=d[x]+1;
			//dist[y]=dist[x]+edge[i];
			f[y][0]=x;
			for (int j=1;j<=t;j++)
			{
				f[y][j]=f[f[y][j-1]][j-1];
			}
			q.push(y);
		}
	}
}
int lca(int x,int y)
{
	if (d[x]>d[y]) swap(x,y);
	for(int k = 20 ; k >= 0 ; --k){
        if(d[f[x][k]] >= d[y])
        {
            x = f[x][k];
        }
    }
	for (int i=t;i>=0;i--)
	{
		if (d[f[y][i]] >= d[x]) y=f[y][i];
	}
	if (x==y) return x;
	for (int i=t;i>=0;i--)
	{
		if (f[x][i] != f[y][i]) x=f[x][i],y=f[y][i];
	}
	return f[x][0];
}
int main()
{
	cin>>n>>m>>T;
	t=(int)(log(n)/log(2))+1;
	for (int i=1;i<=n;i++)
	{
		head[i]=d[i]=0;
	}
	tot=0;
	for (int i=1;i<n;i++)
	{
		int x,y,z=1;
		cin>>x>>y;
		add(x,y,z);add(y,x,z);
	}
	bfs();
	for (int i=1;i<=m;i++)
	{
		int x,y;
		cin>>x>>y;
		cout<<lca(x,y)<<endl;
	}
	return 0;
}