#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<bits/stdc++.h>
using namespace std;
int n,m,s;
int vis[500001];
int father[500001];
map<pair<int,int>,vector<int> > mymap;
vector<int> board[500001];
vector<int> relate[500001];
int ffind(int x)
{
    if(father[x] != x)
    {
        father[x] = ffind(father[x]);
        return father[x];
    }
    return x;
}
void mmerge(int a,int b)
{
    int af = ffind(a);
    int bf = ffind(b);
    father[af] = bf;
    father[a] = bf;
    father[b] = bf;
}
struct Ask
{
    int x,y;
    int ans = -1;
};
Ask asks[500001];
void update(int x,int y,int ans)
{
    for(auto dex : mymap[make_pair(x,y)])
        asks[dex].ans = ans;
}
void dfs(int cur)
{
    vis[cur] = 1;
    int len = board[cur].size();
    for(int i=0;i<len;i++)
    {
        int next = board[cur][i];
        if(vis[next] == 0)
        {
            dfs(next);
            mmerge(next,cur);
        }
    }
    int len2 = relate[cur].size();
    for(int i=0;i<len2;i++)
    {
        int next = relate[cur][i];
        if(vis[next] == 1)
        {
            int ans = ffind(next);
            update(cur,next,ans);
        }
    }
}
int main()
{
    cin >> n >> m >> s;
    for(int i=1;i<=n-1;i++)
    {
        int x,y;
        scanf("%d %d",&x,&y);
        board[x].push_back(y);
        board[y].push_back(x);
    }
    for(int i=1;i<=m;i++)
    {
        int x,y;
        scanf("%d %d",&x,&y);
        asks[i].x = x;
        asks[i].y = y;
        relate[x].push_back(y);
        relate[y].push_back(x);
        mymap[make_pair(x,y)].push_back(i);
        mymap[make_pair(y,x)].push_back(i);
    }
    for(int i=1;i<=n;i++)
        father[i] = i;
    dfs(s);

    for(int i=1;i<=m;i++)
        cout << asks[i].ans << endl;
}