#include <bits/stdc++.h>

using namespace std;

const int N = 500010;

int h[N], e[N * 2], ne[N * 2], idx;
int depth[N], fa[N][22];
int q[N];
int n, m, root;

void add(int a, int b)
{
   e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}

void bfs(int root)
{
    memset(depth, 0x3f, sizeof depth);
    depth[0] = 0, depth[root] = 1;
    int hh = 0, tt = 0;
    q[0] = root;
    while(hh <= tt)
    {
      int t = q[hh++];
      for(int i = h[t]; i != -1; i = ne[i])
       {
          int j = e[i];
          if(depth[j] > depth[t] + 1)
          {
            depth[j] = depth[t] + 1;
             q[++ tt] = j;
             fa[j][0] = t;
   	for(int k = 1; k <= 22; k ++)
        fa[j][k] = fa[fa[j][k - 1]][k - 1];
            }
        }
    }
}

int lca(int a, int b)
{
    if(depth[a] < depth[b]) swap(a, b);
    for(int k = 22; k >= 0; k --)
        if(depth[fa[a][k]] >= depth[b])
            a = fa[a][k];
    if(a == b) return a;
    for(int k = 22; k >= 0;  k --)
      if(fa[a][k] != fa[b][k])
       {
           a = fa[a][k];
           b = fa[b][k];
       }
    return fa[a][0];
}

 
int main()
{
    //输入n,m,root
    cin >> n >> m >> root;
    
    memset(h, -1, sizeof h);
    
    for(int i = 1; i < n; i ++)
    {
        int x, y;
        cin >> x >> y;
        add(x, y);
        add(y, x);
    }
    //预处理 fa数组 和 depth数组
    bfs(root);
    //m次询问
    while(m --)
    {
        int a, b;
        cin >> a >> b;
        int p = lca(a, b);
        cout << p << endl;
    }
    return 0;
}