#include<iostream>#include<cstdio>#include<cstring>#include<map>#include<vector>using namespace std;const int maxn = 111111;struct edge{    int to; int next;}e[maxn * 10];int len;int head[maxn];struct Node{    int val; int id;}vis[maxn], dp[maxn][20];int pos[maxn];int cnt;void add(int from, int to){    e[len].to = to;    e[len].next = head[from];    head[from] = len++;}void dfs(int x, int val){    vis[cnt].val = val; vis[cnt].id = x; pos[x] = cnt++;    for (int i = head[x]; i != -1; i = e[i].next){        int cc = e[i].to;        dfs(cc, val + 1);        vis[cnt].val = val; vis[cnt].id = x; pos[x] = cnt++;    }}void init(int k){    for (int i = 0; i < k; i++)        dp[i][0] = vis[i];    for (int j = 1; (1 << j) <= k; j++){        for (int i = 0; i + (1 << j) - 1 < k; i++){            if (dp[i][j - 1].val < dp[i + (1 << (j - 1))][j - 1].val)                dp[i][j] = dp[i][j - 1];            else dp[i][j] = dp[i + (1 << (j - 1))][j - 1];        }    }}int ask(int l, int r){    int k = 0;    while ((1 << (k + 1)) < r - l + 1) k++;    if (dp[l][k].val < dp[r - (1 << k) + 1][k].val) return dp[l][k].id;    else return dp[r - (1 << k) + 1][k].id;}int main(){    int T; int n;    cin >> T;    int root;    int gg[maxn];    int a, b;    while (T--){        cin >> n;        len = 0;        memset(head, -1, sizeof(head));        for (int i = 1; i <= n; i++) gg[i] = 0;        for (int i = 0; i<n - 1; i++){            scanf("%d%d", &a, &b);            add(a, b); gg[b] = 1;        }        for (int i = 1; i <= n; i++) if (!gg[i]) {            root = i; break;        }        cnt = 0;        dfs(root, 1);        init(cnt);        cin >> a >> b;        int l = pos[a]; int r = pos[b];        if (l>r) swap(l, r);        cout << ask(l, r) << endl;    }    return 0;}