// luogu-judger-enable-o2

#include<bits/stdc++.h>

#define maxn 1000002

//#define int long long

//#define kcz

using namespace std;

inline int read()

{

    char x = getchar();

    int lin = ,f = ;

    while(x < '' || x > '')

    {

        if(x == '-') f = -;

        x = getchar();

    }

    while(x >= '' && x <= '')

    {

        lin = (lin << ) + (lin << ) + x - '';

        x = getchar();

    }

    return lin * f;

}

#define PII pair<int,int>

#define fir first

#define sec second

#define ma(a,b) make_pair(a,b)

#define inf 123123123

int head[maxn],u,v,tot,n,m,dep[maxn],q,fa[maxn][],rt;

struct st{

    int v,nex;

}s[maxn];

void add(int u,int v)

{

    s[++tot] = (st) { v,head[u] };

    head[u] = tot;

}

void dfs(int now,int F)

{

    fa[now][] = F;dep[now]=dep[F]+;

    for(int i=;i<=;i++)fa[now][i]=fa[fa[now][i-]][i-];

    for(int i = head[now]; i; i = s[i].nex)

        if(s[i].v != F)

        {

            dfs(s[i].v,now);

        }

}

int lca(int a,int b)

{

    if(dep[a] > dep[b]) swap(a,b);

    int len = dep[b] - dep[a];

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

        if(len & ( << i))

            b = fa[b][i];

    if(a != b)

    {

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

        {

            if(fa[a][i] != fa[b][i])

            {

                a = fa[a][i];

                b = fa[a][i];

            }

        }

        a = fa[a][];

    }

    return a;

}

signed main(){

    n = read(); q = read(); rt = read();

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

    {

        u = read(); v = read();

        add(u,v); add(v,u);

    }

    dfs(rt,);

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

    {

        u = read(); v = read();

        printf("%d\n",lca(u,v));

    }

}