#include <bits/stdc++.h>
using namespace std;
int n,m,s;
vector<int> adj[500000];

int depth[500000];
int parent[500000][20];

void dfs(int u, int p) {
    depth[u] = depth[p] + 1;
    parent[u][0] = p;
    for (int i = 1; i <= 19; i++) {
        parent[u][i] = parent[parent[u][i - 1]][i - 1];
    }
    for (int i = 0;i < adj[u].size(); i++) {
        int v = adj[u][i];
        if (v == p) {
            continue;
        }
        dfs(v, u);
    }
}

int LCA(int x,int y) {
    if (depth[x] < depth[y]) {
        swap(x, y);
    }

    for (int i = 19; i >= 0; i--) {
        if (depth[parent[x][i]] >= depth[y]) {
            x = parent[x][i];
        }
    }
    if (x == y) {
        return x;
    }
    for (int i = 19; i >= 0; i--) {
        if (parent[x][i] != parent[y][i]) {
            x = parent[x][i];
            y = parent[y][i];
        }
    }

    return parent[x][0];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    cin >> n >> m >> s;
    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    dfs(s, 0);
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        cout << LCA(x, y) << '\n';
    }


    return 0;
}