欢迎复制模板喵 | #【模板】最近公共祖先（LCA）#

#include <bits/stdc++.h>

#define x first
#define y second
#define all(x) x.begin(), x.end()
#define vec1(T, name, n, val) vector<T> name(n, val)
#define vec2(T, name, n, m, val) vector<vector<T>> name(n, vector<T>(m, val))
#define vec3(T, name, n, m, k, val) vector<vector<vector<T>>> name(n, vector<vector<T>>(m, vector<T>(k, val)))
#define vec4(T, name, n, m, k, p, val) vector<vector<vector<vector<T>>>> name((n), vector<vector<vector<T>>>((m), vector<vector<T>>((k), vector<T>((p), (val)))))

using namespace std;
using i128 = __int128;
using u128 = unsigned __int128;
using LL = long long;
using LD = long double;
using ULL = unsigned long long;
using PII = pair<int, int>;
using PLL = pair<LL, LL>;
using PLD = pair<LD, LD>;

const int N = 1e5 + 10, MOD = 998244353;
const int INF = 1e9;
const LL LL_INF = 2e18;
const LD EPS = 1e-8;
const int dx4[] = {-1, 0, 1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {-1, -1, -1, 0, 0, 1, 1, 1}, dy8[] = {-1, 0, 1, -1, 1, -1, 0, 1};
const int hx[] = {-2, -2, -1, -1, 1, 1, 2, 2}, hy[] = {-1, 1, -2, 2, -2, 2, -1, 1};

istream& operator>>(istream& is, i128& val) {
    string str;
    is >> str;
    val = 0;
    bool flag = false;
    if (str[0] == '-') flag = true, str = str.substr(1);
    for (char& c : str) val = val * 10 + c - '0';
    if (flag) val = -val;
    return is;
}

ostream& operator<<(ostream& os, i128 val) {
    if (val < 0) os << "-", val = -val;
    if (val > 9) os << val / 10;
    os << static_cast<char>(val % 10 + '0');
    return os;
}

bool cmp(LD a, LD b) {
    if (fabs(a - b) < EPS) return 1;
    return 0;
}

LL qpow(LL a, LL b) {
    LL ans = 1;
    a %= MOD;
    while (b) {
        if (b & 1) ans = ans * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return ans;
}

struct LCA {
    int n, LOG;
    vector<vector<int>> g;
    vector<vector<int>> fa;
    vector<int> depth;

    LCA(int _n) : n(_n), g(_n + 1) {
        LOG = 32 - __builtin_clz(max(1, n));
        fa.assign(n + 1, vector<int>(LOG, 0));
        depth.assign(n + 1, 0);
    }

    void add(int u, int v) {
        g[u].push_back(v);
        g[v].push_back(u);
    }

    void dfs(int u, int p) {
        fa[u][0] = p;
        depth[u] = depth[p] + 1;
        for (int i = 1; i < LOG; i++) {
            fa[u][i] = fa[fa[u][i - 1]][i - 1];
        }
        for (int v : g[u]) {
            if (v != p) {
                dfs(v, u);
            }
        }
    }

    void build(int root = 1) {
        depth[0] = 0;
        dfs(root, 0);
    }

    int query(int u, int v) {
        if (depth[u] < depth[v]) swap(u, v);

        for (int i = LOG - 1; i >= 0; i--) {
            if (depth[u] - (1 << i) >= depth[v]) {
                u = fa[u][i];
            }
        }

        if (u == v) return u;

        for (int i = LOG - 1; i >= 0; i--) {
            if (fa[u][i] != fa[v][i]) {
                u = fa[u][i];
                v = fa[v][i];
            }
        }

        return fa[u][0];
    }

    int dist(int u, int v) {
        return depth[u] + depth[v] - 2 * depth[query(u, v)];
    }
};

void solve() {
    int n, q, rt;
    cin >> n >> q >> rt;
    LCA lca(n);
    for (int i = 1; i < n; ++i) {
        int a, b;
        cin >> a >> b;
        lca.add(a, b);
    }

    lca.build(rt);

    while (q--) {
        int a, b;
        cin >> a >> b;
        cout << lca.query(a, b) << '\n';
    }
/**/ #ifdef LOCAL
    cout << flush;
/**/ #endif
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    int T = 1;
    while (T--) solve();
    cout << fixed << setprecision(15);

    return 0;
}