#include <stdio.h>
#include <string.h>
#define size 10010
int sets[size];
int flag[size];
int n;
void make_set()
{
    int i;
    for(i=1;i<=n;i++)
    sets[i]=i;
}
int find_set(int x)
{
    int y=sets[x];
    flag[x]=1;
    if(x==y)
    return y;
    else
    {
        y=find_set(y);
        sets[x]=y;
        return y;
    }
}
int result(int n)
{
    if(flag[n])
    return n;
    else
    return result(sets[n]);
}
int main()
{
    int cases,i,father,son,x,y;
    scanf("%d",&cases);
    while(cases--)
    {
        scanf("%d",&n);
        make_set();
        for(i=1;i<n;i++)
        {

            scanf("%d %d",&father,&son);
            sets[son]=father;
        }
		//for(i=1;i<=n;i++)
		//printf("%d\n",sets[i]);
        memset(flag,0,sizeof(flag));
        scanf("%d %d",&x,&y);
		//printf("%d %d\n",x,y);
        find_set(x);
		//for(i=1;i<=n;i++)
		//printf("%d\n",sets[i]);
        printf("%d\n",result(y));
    }
    return 1;
}