#include <bits/stdc++.h>

using namespace std;

struct thing{
    int x, d;
    bool operator<(const thing &obj)const{
        return d < obj.d;
    }
}pd[20][400005];

int n, t, a, b, nodes[200005], euclid[400005], p, first[200005], depth[200005], lg2[400005], up[20][200005], tt[200005];
vector<int> v[200005];

thing make_thing (int x, int d)
{
    thing aux;
    aux.x = x;
    aux.d = d;
    return aux;
}

void build_rmq()
{
    for (int i = p; i > 0; --i){
        pd[0][i] = make_thing(euclid[i], depth[euclid[i]]);
        for (int d = 1; i+(1<<d) <= p; ++d)
            pd[d][i] = min(pd[d-1][i], pd[d-1][i+(1<<(d-1))]);
    }
}

int rmq_query(int x, int y)
{
    if(x == y)
        return x;
    if(first[x] > first[y])
        swap(x, y);
    int lg = lg2[first[y]-first[x]];
    return min(pd[lg][first[x]], pd[lg][first[y]-(1<<lg)]).x;
}

void df(int x, int pred = 0)
{
    depth[x] = depth[pred] + 1;
    tt[x] = pred;
    //up[0][]
    euclid[++p] = x;
    first[x] = p;
    vector<int>::iterator er;
    for (vector<int>::iterator it = v[x].begin(); it != v[x].end(); ++it)
        if(*it == pred)
            er = it;
        else{
            df(*it, x);
            euclid[++p] = x;
        }
    if(x != 1)
        v[x].erase(er);
}

int dist(int u1, int u2)
{

}

int main()
{
    ifstream fin ("lca.in");
    ofstream fout ("lca.out");
    fin >> n >> t;
    for (int i = 1; i < n; ++i){
        int x, y;
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    df(1);
    lg2[2] = 1;
    for (int i = 3; i < 400005; ++i)
        lg2[i] = lg2[i/2]+1;
    build_rmq();


    fin >> a >> b;
    nodes[1] = a;
    nodes[2] = b;
    fout << rmq_query(a, b);
    for (int i = 2; i <= t; ++i){
        /*int u;
        fin >> u;
        nodes[i] = u;*/
        int x, y;
        fin >> x >> y;
        fout << rmq_query(x, y) << "\n";
    }
    fin.close();
    fout.close();
    return 0;
}