#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cstring>

#include <cmath>

using namespace std;

typedef long long ll;

const int N=5e5+;

inline int read(){

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

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

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

    return x*f;

}

int n,q,root,a,b;

struct edge{

    int v,ne;

}e[N<<];

int cnt=,h[N];

inline void ins(int u,int v){

    cnt++;

    e[cnt].v=v;e[cnt].ne=h[u];h[u]=cnt;

    cnt++;

    e[cnt].v=u;e[cnt].ne=h[v];h[v]=cnt;

}

int fa[N][],deep[N],vis[N];

void dfs(int u){

    vis[u]=;

    for(int j=;(<<j)<=deep[u];j++)

        fa[u][j]=fa[fa[u][j-]][j-];

    for(int i=h[u];i;i=e[i].ne){

        int v=e[i].v;

        if(vis[v]) continue;

        deep[v]=deep[u]+;

        fa[v][]=u;

        dfs(v);

    }

}

int lca(int x,int y){

    if(deep[x]<deep[y]) swap(x,y);

    int bin=deep[x]-deep[y];

    for(int i=;i<=;i++)

        if((<<i)&bin) x=fa[x][i];//,printf("x %d\n",i);

    for(int i=;i>=;i--)

        if(fa[x][i]!=fa[y][i]){

            x=fa[x][i];

            y=fa[y][i];

        }

    if(x==y) return x;

    else return fa[x][];

}

int main(int argc, const char * argv[]) {

    n=read();q=read();root=read();

    for(int i=;i<=n-;i++) a=read(),b=read(),ins(a,b);

    dfs(root);

    for(int i=;i<=q;i++){

        a=read();b=read();

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

    }

    return ;

}

#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cstring>

#include <cmath>

using namespace std;

typedef long long ll;

const int N=5e5+;

inline int read(){

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

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

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

    return x*f;

}

int n,q,root,a,b;

struct edge{

    int v,ne;

}e[N<<];

int cnt=,h[N];

inline void ins(int u,int v){

    cnt++;

    e[cnt].v=v;e[cnt].ne=h[u];h[u]=cnt;

    cnt++;

    e[cnt].v=u;e[cnt].ne=h[v];h[v]=cnt;

}

int fa[N],deep[N],mx[N],size[N];

void dfs(int u){

    size[u]++;

    for(int i=h[u];i;i=e[i].ne){

        int v=e[i].v;

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

        fa[v]=u;deep[v]=deep[u]+;

        dfs(v);

        size[u]+=size[v];

        if(size[v]>size[mx[u]]) mx[u]=v;

    }

}

int tid[N],top[N],tot;

void dfs(int u,int anc){

    if(!u) return;

    tid[u]=++tot;top[u]=anc;

    dfs(mx[u],anc);

    for(int i=h[u];i;i=e[i].ne){

        int v=e[i].v;

        if(v!=fa[u]&&v!=mx[u]) dfs(v,v);

    }

}

int lca(int x,int y){

    while(top[x]!=top[y]){

        if(deep[top[x]]<deep[top[y]]) swap(x,y);

        x=fa[top[x]];

    }

    if(deep[x]>deep[y]) swap(x,y);

    return x;

}

int main(int argc, const char * argv[]) {

    n=read();q=read();root=read();

    for(int i=;i<=n-;i++) a=read(),b=read(),ins(a,b);

    dfs(root);

    dfs(root,root);

    for(int i=;i<=q;i++){

        a=read();b=read();

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

    }

    return ;

}