#include <bits/stdc++.h>

using namespace std;

inline long long read()
{
    long long x = 0;
    int f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    return x * f;
}
void write(const long long &x)
{
    if (!x)
    {
        putchar('0');
        return;
    }
    char f[100];
    long long tmp = x;
    if (tmp < 0)
    {
        tmp = -tmp;
        putchar('-');
    }
    long long s = 0;
    while (tmp > 0)
    {
        f[s++] = tmp % 10 + '0';
        tmp /= 10;
    }
    while (s > 0)
    {
        putchar(f[--s]);
    }
}

long long totN;
long long totQ;
int head[500090];
int rot;
struct Edge
{
    int nxt;
    int to;
} edges[1000090];
int cnt_edges;
int lg[1000090];
int fa[500090][35];
int deepth[500090];
void add_edge(int x, int y)
{
    ++cnt_edges;
    edges[cnt_edges].nxt = head[x];
    head[x] = cnt_edges;
    edges[cnt_edges].to = y;
}
void getLOG()
{
    for (int i = 1; i <= totN; i++)
    {
        lg[i] = lg[i - 1] + (1 << lg[i - 1] == i);
    }
}
int DFS(int nowX, int fath)
{
    fa[nowX][0] = fath;
    deepth[nowX] = deepth[fath] + 1;
    for (int i = 1; i <= lg[deepth[nowX]]; i++)
    {
        fa[nowX][i] = fa[fa[nowX][i - 1]][i - 1];
    }
    for (int i = head[nowX]; i; i = edges[i].nxt)
    {
        if (edges[i].to == fath)
        {
            continue;
        }
        DFS(edges[i].to, nowX);
    }
}
int LCA(int x, int y)
{
    if (deepth[x] < deepth[y])
    {
        swap(x, y);
    }
    while (deepth[x] > deepth[y])
    {
        x = fa[x][lg[deepth[x] - deepth[y] - 1]];
    }
    if (x == y)
    {
        return x;
    }
    for (int i = lg[deepth[x]] - 1; i >= 0; --i)
    {
        if (fa[x][i] != fa[y][i])
        {
            x = fa[x][i];
            y = fa[y][i];
        }
    }
    return fa[x][0];
}

int main()
{
    totN = read();
    totQ = read();
    rot = read();
    for (int i = 1; i <= totN - 1; i++)
    {
        int x, y;
        x = read();
        y = read();
        add_edge(x, y);
        add_edge(y, x);
    }
    getLOG();
    DFS(rot, 0);
    for (int i = 1; i <= totQ; i++)
    {
        int x, y;
        x = read();
        y = read();
        write(LCA(x, y));
        putchar('\n');
    }
    return 0;
} //LikiBlaze Code

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