#include<iostream>
#include<cstdio>
using namespace std;
const int N = 5e6;
struct Edge
{
    int to, next;
}e[N << 1];
int cnt = 0;
int head[N << 1];
void add(int from, int to)
{
    e[++cnt].to = to;
    e[cnt].next = head[from];
    head[from] = cnt;
}
int fa[N], dep[N];
int f[N][21];
void dfs(int x)
{
    for (int i = head[x]; i; i = e[i].next)
    {
        int v = e[i].to;
        if (v != fa[x])
        {
            dep[v] = dep[x] + 1;
            f[v][0] = fa[v] = x;
            dfs(v);
        }
    }
}
int lca(int x, int y)
{
    if (dep[x] > dep[y]) swap(x, y);
    for (int i = 20; i >= 0; i--)
        if (dep[f[y][i]] >= dep[x])
            y = f[y][i];
    if (x == y) return x;
    for (int i = 20; i >= 0; i--)
    {
        if (f[y][i] != f[x][i])
        {
            x = f[x][i];
            y = f[y][i];
        }
    }
    return fa[x];
}
int main()
{
    int n, m, s;
    scanf("%d%d%d", &n, &m, &s);
    int u, v;
    for (int i = 1; i < n; i++)
    {
        scanf("%d%d", &u, &v);
        add(u, v);
        add(v, u);
    }
    fa[s] = f[s][0] = s;
    dfs(s);
    for (int x = 1; x <= n; x++)
        for (int i = 1; i <= 20; i++)
            f[x][i] = f[f[x][i - 1]][i - 1];
    for (int i = 1; i <= m; i++)
    {
        scanf("%d%d", &u, &v);
        printf("%d\n", lca(u, v));
    }
    return 0;
}