#include <iostream>
#include <vector>
using namespace std;

const int MAX_N = 100005;  
const int MAX_LOG = 20;

vector<int> adj[MAX_N];     
int parent[MAX_N][MAX_LOG];

int depth[MAX_N];

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

void preprocess(int root, int n) {
    dfs(root, -1, 0);
    for (int j = 1; j < MAX_LOG; j++) {
        for (int i = 0; i < n; i++) {
            if (parent[i][j-1] != -1) {
                parent[i][j] = parent[parent[i][j-1]][j-1];
            }
        }
    }
}

int lca(int u, int v) {
    if (depth[u] < depth[v]) {
        swap(u, v);
    }
    for (int i = MAX_LOG - 1; i >= 0; i--) {
        if (depth[u] - (1 << i) >= depth[v]) {
            u = parent[u][i];
        }
    }
    if (u == v) {
        return u;
    }
    for (int i = MAX_LOG - 1; i >= 0; i--) {
        if (parent[u][i] != parent[v][i]) {
            u = parent[u][i];
            v = parent[v][i];
        }
    }
    return parent[u][0];
}

int main() {
    int n, m, root;
    cin >> n >> m >> root;

    for (int i = 0; i < n - 1; i++) {
        int x, y;
        cin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }

    preprocess(root, n);

    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        cout << lca(a, b) << endl;
    }

    return 0;
}