#include <bits/stdc++.h>
using namespace std;
#define ll long long int
ll n,t,u,v,a,b,s[100007][3];
std::vector<ll> adj[100007];
void dfs(ll cur, ll par, ll i){
  s[i][cur] = 1;
  printf("visiting %d\n", cur);
  for(ll v: adj[cur])
    if(par!=v) dfs(v, cur, i), s[i][cur]+=s[i][v];
}
int main(){
  std::cin >> t;
  while (t--) {
    memset(s, 0, sizeof(s));
    for(ll i = 0; i<=n; i++) adj[i].clear();
    std::cin >> n >> a >> b;
    for(ll i = 0; i<n-1; i++){
      std::cin >> u >> v;
      adj[u].push_back(v);
      adj[v].push_back(u);
    }
    dfs(a,0,0);
    for(ll i = 1; i<=n; i++){
      // printf("s[0][%lld] = %lld\n", i, s[0][i]);
    }
    printf("\n\n");
    dfs(b,0,1);
    for(ll i = 1; i<=n; i++){
      // printf("s[0][%lld] = %lld\n", i, s[1][i]);
    }
    ll res1 = (n-s[0][b])*s[0][b];
    ll res2 = (n-s[1][a])*s[1][a];
    ll res3 = s[0][b]*s[1][a];
    // printf("res1 = %lld, res2 = %lld, res3 = %lld\n", res1, res2, res3);
    std::cout << res1+res2-res3 << '\n';
  }
}