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#include <cmath>
#include <cstdio>
#include <iostream>
#include <vector>

using namespace std;

#define MAX 500000

vector<int> tree[MAX];
int dep[MAX];
int fas[MAX];

namespace M1 {
    void dfs(int x, int fa) {
        if (fa != -1) {
            dep[x] = dep[fa] + 1;
        }
        fas[x] = fa;
        for (int i = 0; i < tree[x].size(); i++) {
            if (fas[tree[x].at(i)] == -2) M1::dfs(tree[x].at(i), x);
        }
    }


    int solve(int a, int b) {
        while (1) {
            if (a == b) {
                return a;
            } else if (fas[a] == fas[b]) {
                return fas[a];
            } else if (fas[b] == a) {
                return a;
            } else if (fas[a] == b) {
                return b;
            }
            int da = dep[a], db = dep[b];
            int delta = abs(da - db);
            if (da > db) {
                for (int i = 0; i < delta; i++) {
                    a = fas[a];
                    da = dep[a];
                }
            } else if (da < db) {
                for (int i = 0; i < delta; i++) {
                    b = fas[b];
                    db = dep[b];
                }
            } else {
                a = fas[a];
                da = dep[a];
            }
        }
        return -1;
    }
}

bool first = true;

int LCA(int a, int b, int r) {
    if (first) {
        M1::dfs(r, -1);
        first = false;
    }
    int res;
    res = M1::solve(a, b);
    return res;
}

int main(int argc, char *argv[]) {
    int m, n, s;
    cin >> m >> n >> s;
    for (int i = 0; i < MAX; i++) {
        dep[i] = 0;
        fas[i] = -2;
    }
    for (int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        tree[x].push_back(y);
        tree[y].push_back(x);
    }
    dep[s] = 0;
    fas[s] = -1;
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        int res = LCA(a, b, s);
        cout << res << endl;
    }
    return 0;
}

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#include <cmath>
#include <cstdio>
#include <iostream>
#include <vector>

using namespace std;

#define MAX 500001 
#define MUL_MAX 22

vector<int> tree[MAX]; 
int dep[MAX]; 
int fas[MAX][MUL_MAX]; 
bool first = true; 

int lg2(int x) {
    return log(x) / log(2) + 1; 
} 

void dfs(int x, int fa) { 
    if (fa != -1) {
        dep[x] = dep[fa] + 1; 
    }
    fas[x][0] = fa; 
    for (int i = 1; (1 << i) <= dep[x]; i++) { 
        fas[x][i] = fas[fas[x][i - 1]][i - 1]; 
        
        
        
    }
    for (int i = 0; i < tree[x].size(); i++) {
        if (tree[x].at(i) != fa) dfs(tree[x].at(i), x); 
        
    }
} 

int solve(int a, int b) {
    if (dep[b] > dep[a]) swap(a, b); 
    while (dep[a] > dep[b]) {
        a = fas[a][lg2(dep[a] - dep[b]) - 1]; 
    }
    if (a == b) return a; 
    for (int i = lg2(dep[a]); i >= 0; i--) {
        if (fas[a][i] != fas[b][i]) {
            a = fas[a][i];
            b = fas[b][i];
        }
    } 
    return fas[a][0]; 
}

int LCA(int a, int b, int r) {
    if (first) {
        dep[r] = 0;
        fas[r][0] = -1;
        dfs(r, -1);
        first = false;
    }
    int res;
    res = solve(a, b);
    return res;
}

int main(int argc, char *argv[]) {
    int m, n, s;
    cin >> m >> n >> s;
    for (int i = 0; i < MAX; i++) {
        dep[i] = 0;
        for (int j = 0; j < MUL_MAX; j++)
            fas[i][j] = -2;
    } 
    for (int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        tree[x].push_back(y);
        tree[y].push_back(x);
        
    }
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        int res = LCA(a, b, s);
        cout << res << endl;
    }
    return 0;
}