#include <bits/stdc++.h>
using namespace std;

#define int long long
#define maxn 1000005
int n, q, s;
int tot, t;
int ver[maxn], head[maxn], Next[maxn];
int f[maxn][205], d[maxn];

void add(int x, int y) {
    ver[++tot] = y;
    Next[tot] = head[x], head[x] = tot;
}

void build() {
    queue<int> q;
    q.push(s); d[s] = 1;
    while (q.size()) {
        int x = q.front(); q.pop();
        for (int i = head[x]; i; i = Next[i]) {
            int y = ver[i];
            if (d[y]) continue;
            d[y] = d[x] + 1, f[y][0] = x;
            for (int j = 1; j <= t; j++) {
                //if (pow(2, j - 1) >= d[y]) break;
                f[y][j] = f[f[y][j - 1]][j - 1];
            }
            q.push(y);
        }
    }
}

int get_lca(int x, int y) {
    if (d[x] < d[y]) swap(x, y);
    for (int i = t; i >= 0; i--)
        if (d[f[x][i]] >= d[y]) x = f[x][i];
    if (x == y) return x;
    for (int i = t; i >= 0; i--)
        if (f[x][i] != f[y][i]) x = f[x][i], y = f[y][i];
    return f[x][0];
}

signed main() {
    cin >> n >> q >> s;
    t = log(n); if (t * t != n) t++;
    for (int i = 1; i <= n; i++) {
        int x, y;
        cin >> x >> y;
        add(x, y), add(y, x);
    }
    build();
    while (q--) {
        int x, y;
        cin >> x >> y;
        cout << get_lca(x, y) << endl;
    }
    return 0;
}