#include <bits/stdc++.h>

using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 500010, M = 500010 * 2;
//邻接表
int e[M], h[N], idx, ne[M];
void add(int a, int b) {
    e[idx] = b, ne[idx] = h[a], h[a] = idx++;
}

int dep[N];
int f[N][22];
void bfs(int t) {
    dep[t] = 1;
    queue<int> q;
    q.push(t);
    while (q.size()) {
        int u = q.front();
        q.pop();
        for (int i = h[u]; ~i; i = ne[i]) {
            int j = e[i];
            if (!dep[j]) {
                dep[j] = dep[u] + 1;
                q.push(j);
                f[j][0] = u;
                for (int k = 1; k <= 20; k++)
                    f[j][k] = f[f[j][k - 1]][k - 1];
            }
        }
    }
}
int lca(int a, int b) {
    if (dep[a] < dep[b]) swap(a, b);
    for (int k = 20; k >= 0; k--)
        if (dep[f[a][k]] >= dep[b]) a = f[a][k];
    if (a == b) return a;
    for (int k = 20; k >= 0; k--)
        if (f[a][k] != f[b][k])
            a = f[a][k], b = f[b][k];
    return f[a][0];
}
int main() {
    memset(h, -1, sizeof h);
    int n, m, s;
    cin >> n >> m >> s;
    int a, b;
    for (int i = 0; i < n - 1; i++) {
        cin >> a >> b;
        add(a, b), add(b, a);
    }
    bfs(s);
    for (int i = 1; i <= m; i++) {
        cin >> a >> b;
        printf("%d\n", lca(a, b));
    }
    return 0;
}