// zhe ge wo ye dong le ha ha ha ha ha !

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

struct zzz 
{
    int t, nex;
}e[500010 << 1]; int head[500010], tot;

void add(int x, int y) 
{
    e[++tot].t = y;
    e[tot].nex = head[x];
    head[x] 
 
= tot;
}

int depth[500001], fa[500001][22], lg[500001];

void dfs(int now, int fath) 
{
    fa[now][0] = fath; 
    depth[now] = depth[fath] + 1;
    
    for(int i = 1; i <= lg[depth[now]]; ++i)
        fa[now][i] = fa[fa[now][i-1]][i-1];
    
    for(int i = head[now]; i; i = e[i].nex)
        if(e[i].t != fath) 
        dfs(e[i].t, now);
        
}

 
int LCA(int x,int y)
{
    
    if(depth[x]<depth[y])
    swap(x,y);
    
    while(depth[x]>depth[y])//tiao dao tong yi ceng
    x=fa[x][lg[depth[x]-depth[y]]-1];
    
    if(x==y)
    return x;
    
    for(int k=lg[depth[x]]-1;k>=0;--k)//qing gao dong zhe li
    {
        if(fa[x][k]!=fa[y][k])
        x
 
=fa[x][k],y=fa[y][k];
    }
    
    return fa[x][0];
    
}

int main() 
{
    int n, m, s; scanf("%d%d%d", &n, &m, &s);
    
    for(int i = 1; i <= n-1; ++i) 
    {
        int x, y; scanf("%d%d", &x, &y);
        add(x, y); add(y, x);
    }
    
    for(int i = 1; i <= n; ++i)
        lg[i] = lg[i-1] + (1 << lg[i-1] == i);
    dfs(s, 0);
    
    for(int i = 1; i <= m; ++i) 
    {
        int x, y; scanf("%d%d",&x, &y);
        printf("%d\n", LCA(x, y));
    }
    return 0;
}