#include<bits/stdc++.h>
using namespace std;
/*#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
/*template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
*/typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pl;
typedef pair<int,int> pii;

#define LOCAL 0
#define dbg(x) cout << #x << " is " << x << "\n"
#define gll(x) scanf("%d",&x)
#define gll2(x,y) scanf("%d%d",&x,&y)
#define gll3(x,y,z) scanf("%d%d%d",&x,&y,&y)
#define gllarr(arr,n) f(i,n) gll(arr[i]);
#define sz(x) ((int)x.size())
#define s(x) sort(x.begin(),x.end())
#define all(v) v.begin(),v.end()
#define rs(v) { s(v) ; r(v) ; }
#define r(v) {reverse(all(v));}
#define pb push_back
#define F first
#define S second
#define f(i,n) for(int i=0;i<n;i++)
#define fr(i,n) for(int i=n-1;i>=0;i--)
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define repr(i,a,b) for(int i=a;i>=b;i--)

const ll mod = 1000000007;
const ll inf = (ll)1e17;
const ld eps = 1e-12;
const ll N = (int)1e5+2;
const ll LOGN = 19;
const ld PI = 3.14159265358979323846;
ll mul(ll a, ll b, ll m = mod) { return (ll)(a * b) % m;}
ll add(ll a, ll b, ll m = mod) { a += b; if(a >= m) a -= m; if(a < 0) a += m; return a;}
ll power(ll a, ll b, ll m = mod) { if(b == 0) return 1; if(b == 1) return (a % m); ll x = power(a, b / 2, m); x = mul(x, x, m); if(b % 2) x = mul(x, a, m); return x;}

ll n,a,b;
vector<ll> adj[N];
ll sz[N];
ll par[N];

void dfs(ll src,ll parent)
{
    sz[src] = 1;
    for(ll i : adj[src]){
        if(i != parent) {
            par[i] = src;
            dfs(i, src);
            sz[src] += sz[i];
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    if (LOCAL) {
        freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\input.txt", "r", stdin);
        freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\output.txt", "w", stdout);
    }
    int t;
    cin>>t;
    while(t--)
    {
        cin>>n>>a>>b;
        f(i,n+1){
            par[i] = -1;
            sz[i] = 0;
            adj[i].clear();
        }
        f(i,n-1)
        {
            ll u,v;
            cin>>u>>v;
            adj[u].pb(v);
            adj[v].pb(u);
        }
        par[a] = a;
        dfs(a,a);
//        rep(i,1,n+1)
//            cout<<sz[i]<<" ";
//        cout<<endl;
        ll ver = par[b];
        ll child = b;
        ll ans = 0;
        while(ver != a) {
            ans += (ll)((ll)(sz[ver] - sz[child]) * (ll)(sz[a] - sz[ver]));
            child = ver;
            ver = par[ver];
        }
        //ll ans = ((ll)(sz[a] - sz[ver]) * (ll)(sz[ver] - sz[b]));
        ans += (ll)((ll)(sz[a] - sz[b]) * (ll)sz[b]);
        cout<<ans<<endl;
    }
    return 0;
}