#include <stdio.h>
#include <string.h>
#define size 10010
int father[size];
int vis[size];
int main()
{
    
    int cases,i,n,f,s,x,y,a,b;
    scanf("%d",&cases);
    while(cases--)
    {
        scanf("%d",&n);
        memset(father,-1,sizeof(father));
        memset(vis,0,sizeof(vis));
        for(i=1;i<n;i++)
        {
            scanf("%d %d",&f,&s);
            father[s]=f;
        }
        scanf("%d %d",&x,&y);
        while(father[x]!=-1)
        {
            vis[x]=1;
            x=father[x];
        }
        while(!vis[y])
        {
            y=father[y];
        }
        printf("%d\n",y);
    }
    return 0;
}