#include <bits/stdc++.h>
using namespace std;
#define REP(i, l, r) for(int i = (l); i < (r); ++i)
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define FORD(i, r, l) for(int i = (r); i >= (l); --i)
#define ff first
#define ss second
#define eb emplace_back
#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(v) (int)v.size()
#define compact(v) v.erase(unique(all(v)), v.end())
#define dbg(v) "[" #v " = " << (v) << "]"
#define el "\n"
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
template<class T> bool minimize(T& a, const T& b){ if(a > b) return a = b, true; return false; }
template<class T> bool maximize(T& a, const T& b){ if(a < b) return a = b, true; return false; }
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
long long randRange(long long l, long long r){ return uniform_int_distribution<long long>(l,r)(rng); }
const int N = 1e6 + 5;
const int LOG = 20;
struct locked_route {
int u, v, h, id;
locked_route(int u = 0, int v = 0, int h = 0, int id = 0) : u(u), v(v), h(h), id(id) {}
};
int n, m, s, t;
vector<pii> adj[N];
vector<locked_route> lkr;
namespace HLD {
int tin[N], tout[N], id[N], siz[N], high[N], dist[N], par[N], head[N], timer_dfs = 0, cur_chain = 0;
void dfs(int u) {
siz[u] = 1;
tin[u] = ++timer_dfs;
for(auto [v, w] : adj[u]) {if (v == par[u]) continue;
high[v] = high[u] + 1;
dist[v] = dist[u] ^ w;
par[v] = u;
dfs(v);
siz[u] += siz[v];
}
tout[u] = timer_dfs;
}
void dfs2(int u) {
if (head[cur_chain] == 0) {
head[cur_chain] = u;
}
id[u] = cur_chain;
int fat = 0;
for(auto [v, w] : adj[u]) { if (v == par[u]) continue;
if (siz[fat] < siz[v]) {
fat = v;
}
}
if (fat != 0) dfs2(fat);
for(auto [v, w] : adj[u]) {
if (v == par[u] || v == fat) continue;
++cur_chain;
dfs2(v);
}
}
int get_lca(int u, int v) {
while(id[u] != id[v]) {
if (id[u] < id[v]) swap(u, v);
u = par[head[id[u]]];
}
return (high[u] < high[v] ? u : v);
}
void preapre_lca() {
dfs(1);
dfs2(1);
}
int get_dist(int u, int v) {
return high[u] + high[v] - 2 * high[get_lca(u, v)];
}
int get_locked(int u, int v) {
return dist[u] ^ dist[v];
}
} using namespace HLD;
bool is_sub(int v, int acs) {
return tin[acs] <= tin[v] && tout[v] <= tout[acs];
}
int key[N], target[N];
ll dp[20][(1 << 20)];
bool can_go(int u, int v, int mask) {
int sub = get_locked(u, v);
return ((sub & mask) == sub);
}
void solve() {
cin >> n >> s >> t;
FOR(i, 1, n - 1) {
int u, v, h;
cin >> u >> v >> h;
int w = 0;
if (h != 0) {
w = (1 << sz(lkr));
lkr.eb(u, v, h, sz(lkr));
++m;
}
adj[u].eb(v, w);
adj[v].eb(u, w);
}
preapre_lca();
if (can_go(s, t, 0)) {
cout << get_dist(s, t) << el;
return;
}
for(auto _ : lkr) {
int u = _.u;
int v = _.v;
int h = _.h;
int id = _.id;
key[id] = h;
if (high[u] > high[v]) swap(u, v);
target[id] = (is_sub(s, v) ? v : u);
}
FOR(i, 0, m - 1) {
REP(mask, 0, (1 << m))
dp[i][mask] = LLONG_MAX;
}
FOR(i, 0, m - 1) {
if (can_go(s, key[i], 0) && can_go(key[i], target[i], 0)) {
dp[i][(1 << i)] = get_dist(s, key[i]) + get_dist(key[i], target[i]);
}
}
ll ans = LLONG_MAX;
REP(mask, 0, (1 << m)) {
FOR(i, 0, m - 1) {
if (dp[i][mask] == LLONG_MAX) continue;
FOR(j, 0, m - 1) {
if (!(mask >> j & 1)) {
if (can_go(target[i], key[j], mask) &&
can_go(key[j], target[j], mask)) {
minimize(dp[j][mask | (1 << j)],
dp[i][mask] + get_dist(target[i], key[j])
+ get_dist(key[j], target[j]));
}
}
}
if (can_go(target[i], t, mask)) {
minimize(ans, dp[i][mask] + get_dist(target[i], t));
}
}
}
cout << (ans == LLONG_MAX ? -1 : ans) << el;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
#define task "test"
if(fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
solve();
return 0;
}
/*
*/
