#include <bits/stdc++.h>
using namespace std;
const int N = 500010, M = N << 1;

int e[M], h[N], idx, w[M], ne[M];
void add(int a, int b, int c = 0) {
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
}

int depth[N];
int fa[N];

void bfs(int root) {
    queue<int> q;
    q.push(root);
    depth[root] = 1;
    fa[root] = -1;

    while (q.size()) {
        int u = q.front();
        q.pop();
        for (int i = h[u]; ~i; i = ne[i]) {
            int v = e[i];
            if (!depth[v]) {
                depth[v] = depth[u] + 1;
                fa[v] = u;
                q.push(v);
            }
        }
    }
}

int lca(int a, int b) {
    if (depth[a] > depth[b]) swap(a, b);
    while (depth[a] < depth[b]) b = fa[b];
    while (a != b) a = fa[a], b = fa[b];
    return a;
}
int main() {
#ifndef ONLINE_JUDGE
    freopen("P3379.in", "r", stdin);
#endif
    memset(h, -1, sizeof h);

    int n, m, s;
    scanf("%d %d %d", &n, &m, &s);

    int a, b;
    for (int i = 1; i < n; i++) {
        scanf("%d %d", &a, &b);
        add(a, b), add(b, a);
    }

    bfs(s);

    while (m--) {
        scanf("%d %d", &a, &b);

        cout << lca(a, b) << endl;
    }
    return 0;
}