#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define taskname ""
#define ld long double
using namespace std;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const ll INFLL = (ll)4e18;
int main(){
if (fopen(taskname".inp","r")) {
freopen(taskname".inp","r",stdin);
freopen(taskname".out","w",stdout);
}
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n,s,t;
cin >> n >> s >> t;
struct E{int to; int kid;};
vector<vector<E>> g(n+1);
int curk = 0;
vector<int> keyroom(1,0);
for(int i=0;i<n-1;i++){
int u,v,w; cin>>u>>v>>w;
int kid = 0;
if(w!=0){
curk++;
keyroom.pb(w);
kid = curk;
}
g[u].push_back({v,kid});
g[v].push_back({u,kid});
}
int M = curk;
int sz = M + 1;
if (sz > 23){ cout << -1 << '\n'; return 0; }
vector<int> parent(n+1,0), depth(n+1,0), summask(n+1,0);
vector<int> door_room(sz, -1), keynode(sz, -1);
keynode[0] = s;
door_room[0] = s;
parent[s] = s;
depth[s] = 0;
summask[s] = 0;
vector<int> st; st.pb(s);
while(!st.empty()){
int u = st.back(); st.pop_back();
for(auto &e: g[u]){
int v = e.to;
if(v == parent[u]) continue;
parent[v] = u;
depth[v] = depth[u] + 1;
summask[v] = summask[u];
if(e.kid != 0){
int k = e.kid;
door_room[k] = u;
keynode[k] = keyroom[k];
summask[v] |= (1<<k);
}
st.pb(v);
}
}
int lg = 1; while((1<<lg) <= n) ++lg;
vector<vector<int>> up(lg, vector<int>(n+1));
for(int v=1; v<=n; ++v) up[0][v] = parent[v];
for(int i=1;i<lg;i++) for(int v=1; v<=n; ++v) up[i][v] = up[i-1][ up[i-1][v] ];
auto lca = [&](int a,int b){
if(depth[a] < depth[b]) swap(a,b);
int diff = depth[a] - depth[b];
for(int i=0;i<lg;i++) if(diff & (1<<i)) a = up[i][a];
if(a==b) return a;
for(int i=lg-1;i>=0;i--) if(up[i][a] != up[i][b]) { a = up[i][a]; b = up[i][b]; }
return up[0][a];
};
for(int k=1;k<=M;k++){
if(door_room[k] == -1){
cout << -1 << '\n';
return 0;
}
}
vector<int> dis2(sz,0);
for(int i=0;i<sz;i++){
int u = keynode[i];
int v = door_room[i];
if(u == -1){ dis2[i] = 0; continue; }
int w = lca(u,v);
dis2[i] = depth[u] + depth[v] - 2*depth[w];
}
vector<vector<int>> dis1(sz, vector<int>(sz,0));
for(int i=0;i<sz;i++) for(int j=0;j<sz;j++){
int v = door_room[i], vv = keynode[j];
if(vv == -1){ dis1[i][j] = 0; continue; }
int w = lca(v,vv);
dis1[i][j] = depth[v] + depth[vv] - 2*depth[w];
}
int FULL = 1<<sz;
vector<vector<ll>> dp(sz, vector<ll>(FULL, INFLL));
dp[0][1] = 0;
for(int mask=1; mask<FULL; ++mask){
for(int i=0;i<sz;i++){
if(dp[i][mask] == INFLL) continue;
for(int j=1;j<sz;j++){
if((mask>>j)&1) continue;
int u = keynode[j], v = door_room[j];
int path1 = summask[ door_room[i] ] ^ summask[ u ];
int path2 = summask[ v ] ^ summask[ u ];
if((mask & path1) == path1 && (mask & path2) == path2){
int nm = mask | (1<<j);
ll cost = dp[i][mask] + (ll)dis1[i][j] + (ll)dis2[j];
if(cost < dp[j][nm]) dp[j][nm] = cost;
}
}
}
}
ll ans = INFLL;
for(int mask=0; mask<FULL; ++mask){
for(int i=0;i<sz;i++){
if(dp[i][mask] == INFLL) continue;
int u = door_room[i];
int path = summask[u] ^ summask[t];
int w = lca(u,t);
if((mask & path) == path){
ll total = dp[i][mask] + (ll)(depth[u] + depth[t] - 2*depth[w]);
if(total < ans) ans = total;
}
}
}
if(ans == INFLL) cout << -1;
else cout << ans;
return 0;
}
