#include <bits/stdc++.h>

#define read read()

#define up(i,l,r) for(register int i = (l);i <= (r);i++)

#define down(i,l,r) for(register int i = (l);i >= (r);i--)

#define traversal_vedge(i) for(register int i = head[u]; i ;i = e[i].nxt)

#define ll long long

using namespace std;

int read

{

    int x = , f = ; char ch = getchar();

    while(ch <  || ch > ) {if(ch == '-')f = -; ch = getchar();}

    while(ch >= && ch <=) {x =  * x + ch - ;ch = getchar();}

    return x * f;

}

int n,m,s;

const int N = ;

int dep[N],fa[N],size[N],top[N];

struct edge{

    int v,nxt;

}e[N<<];int cnt,head[N];

void add(int u,int v){

    e[++cnt] = (edge){v,head[u]};

    head[u] = cnt;

}

void readdata()

{

    n = read; m = read; s = read;

    up(i,,n-)

    {

        int u = read,v = read;

        add(u,v);

        add(v,u);

    }

}

//-----------------------------------------------------------------------

void dfs(int u)

{

    dep[u] = dep[fa[u]] + ;

    size[u] = ;

    top[u] = u;

    //debug 未写 top[u] = u;

    int heavyson_id = ,heavyson_size = ;

    traversal_vedge(i)

    {

        int v = e[i].v;

        if(v == fa[u]) continue;

        fa[v] = u; //top[v] = u;

        //debug 不写top[v] = u;

        dfs(v);

        size[u] += size[v];

        //heavyson = max(heavyson,size[v]);

        if(size[v] > heavyson_size) heavyson_id = v,heavyson_size = size[v];

    }

    if(heavyson_id) top[heavyson_id] = u;//debug heavyson_id -> u;

    //有重儿子才更新top[]

    //dfs后,top[]只相当于重链上的fa[] 

    //调用find(u)过后,从u到链首的所有top[]才指向链首;

}

int find(int u)

{

    if(u == top[u]) return u;

    top[u] = find(top[u]);//debug top[u] -> u

    return top[u];

    //逆向搜索,并修改值;

}

int lca(int x,int y)

{

    if(find(x) != find(y)) //如果不在一条链上

    //**一条链:重链为一条链,轻链单独一条边为一条链;

    {

        if(dep[top[x]] > dep[top[y]]) return lca(fa[top[x]] , y);//debug fa[top[x]] -> fa[dep[top[x]]];

        else return lca(x , fa[top[y]]);

    }

    return dep[x] > dep[y] ? y : x;

}

void work()

{

    dfs(s);

    while(m--)

    {

        int a = read,b = read;

        printf("%d\n",lca(a,b));

    }

}

int main()

{

    freopen("input.txt","r",stdin);

    readdata();

    work();

    return ;

}