#include <stdio.h>
#include <stdlib.h>
//void Printing_array(int *arr, int n, char *s);
//int Find_dept(int *tree, int index);
//int Find_anc_by_deptcmp(int *tree, int *dept, int a, int b);
//int test_mode_on = 0;
int tree_m[10001];
int dept_m[10001];
/*
void Print(int n){
printf("\n Tree \n");
for(int i=1; i<n+1; i++){
printf(" %d ", tree_m[i]);
}
printf("\n Dept \n");
for(int i=1; i<n+1; i++){
printf(" %d ", dept_m[i]);
}
printf("\n");
}
*/
int main(void) {
int test_case;
int node_n;
int a, b;
//int *tree, *dept;
int ans;
int first=1;
scanf("%d", &test_case);
for(int k=0; k<test_case; k++){
//Init - make empty tree
scanf("%d", &node_n);
for(int i=0; i<10001; i++){
tree_m[i]= 0;
dept_m[i]=0;
}
//if(test_mode_on) printf("node_n= %d\n", node_n);
//tree = (int *)malloc(sizeof(int) * (node_n+1));
//dept = (int *)malloc(sizeof(int) * (node_n+1));
//Init - allocate
//printf("test case %d, n %d", test_case, node_n);
for(int i=0; i<node_n-1; i++){
scanf("%d %d", &a, &b);
//if(test_mode_on) printf("up= %d, down= %d\n", a, b);
tree_m[b] = a;
}
//if(test_mode_on) Printing_array(tree, node_n, "tree");
//Init - calc dept
for(int i=1; i<node_n+1; i++){
//dept[i] = Find_dept(tree, i);
int p = i;
int d = 1;
while(tree_m[p]!=0){
p=tree_m[p];
d++;
}
dept_m[i]=d;
}
//if(test_mode_on) Printing_array(dept, node_n, "dept");
//Print(node_n);
//Calc
scanf("%d %d", &a, &b);
//if(test_mode_on) printf("\ninput: %d, %d\n", a, b);
//ans = Find_anc_by_deptcmp(tree, dept, a, b);
//printf("find %d %d\n", a ,b);
while(a!=b){
if(dept_m[a] >= dept_m[b]){
a=tree_m[a];
}else {
b=tree_m[b];
}
}
if(!first) printf("\n");
printf("%d", a);
/*
ans = a;
//if(test_mode_on){
// printf("\nans: %d\n");
//}else {
if(!first) printf("\n");
printf("%d", ans);
//}
//free(tree);
//free(dept);
*/
first=0;
}//end for
return 0;
}
/*
void Printing_array(int *arr, int n, char *s){
printf("\n show %s \n", s);
for(int i=1; i<n+1; i++){
printf(" %d ", arr[i]);
}
printf("\n -------------\n");
}
*/
/*
int Find_dept(int *tree, int index){
if(tree[index]==0) return 1;
return Find_dept(tree, tree[index]) + 1;
}
int Find_anc_by_deptcmp(int *tree, int *dept, int a, int b){
if(a == b){
//if(test_mode_on) printf("\n find %d\n", a);
return a;
}else if(dept[a] >= dept[b]){
//if(test_mode_on) printf("\ndept[%d] >= dept[%d] / %d >= %d\n", a, b, dept[a], dept[b]);
return Find_anc_by_deptcmp(tree, dept, tree[a], b);
}else if(dept[a] < dept[b]){
//if(test_mode_on) printf("\ndept[%d] < dept[%d] / %d < %d\n", a, b, dept[a], dept[b]);
return Find_anc_by_deptcmp(tree, dept, a, tree[b]);
}
}
*/
