#include <bits/stdc++.h>
using namespace std;
#define int long long
#define inf 0x3F3F3F3F3F3F3F3F
struct DSU
{
vector<int> e;
void init(int n)
{
e.assign(n + 1, -1);
}
int get(int x)
{
if (e[x] < 0) return x;
return e[x] = get(e[x]);
}
void unite(int x, int y)
{
x = get(x), y = get(y);
if (x == y) return;
if (e[x] > e[y]) swap(x, y);
e[x] += e[y];
e[y] = x;
}
};
const int MXN = 1e6 + 5;
const int LOG = 20;
int n, S, T, A, B, b = 0;
vector<int> adj[MXN];
int p[LOG][MXN], dep[MXN], in[MXN], out[MXN], tim;
int id[MXN];
void dfs(int a)
{
in[a] = ++tim;
for (int &v : adj[a])
{
if (v == p[0][a]) continue;
p[0][v] = a;
dep[v] = dep[a] + 1;
dfs(v);
}
out[a] = tim;
}
vector<array<int, 3>> m;
int anc(int u, int v)
{
return in[u] <= in[v] && out[v] <= out[u];
}
int LCA(int u, int v)
{
if (anc(u, v)) return u;
if (anc(v, u)) return v;
for (int i = LOG - 1; i >= 0; i--)
{
if (anc(p[i][u], v)) continue;
u = p[i][u];
}
return p[0][u];
}
int DIST(int u, int v)
{
return dep[u] + dep[v] - 2 * dep[LCA(u, v)];
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> S >> T;
DSU dsu;
dsu.init(n);
for (int i = 1; i < n; i++)
{
int u, v, w;
cin >> u >> v >> w;
adj[u].push_back(v);
adj[v].push_back(u);
if (!w) dsu.unite(u, v);
else m.push_back({u, v, w});
}
p[0][S] = S;
dfs(S);
for (array<int, 3> &i : m) if (p[0][i[0]] == i[1]) swap(i[0], i[1]);
A = dsu.get(S), B = dsu.get(T);
int ASD = 0;
for (int i = 1; i <= n; i++)
{
if (dsu.get(i) == i) id[i] = ++ASD;
}
for (int i = 1; i < LOG; i++) for (int j = 1; j <= n; j++) p[i][j] = p[i - 1][p[i - 1][j]];
vector<int> o(m.size());
iota(o.begin(), o.end(), 0);
int res = inf;
while (1)
{
DSU d;
d.init(ASD);
int f = 1, cur = S, ans = 0;
for (int &i : o)
{
if (d.get(id[A]) == d.get(id[B])) break;
if (d.get(id[dsu.get(m[i][0])]) != d.get(id[A]) || d.get(id[dsu.get(m[i][2])]) != d.get(id[A]))
{
f = 0;
break;
}
d.unite(id[dsu.get(m[i][1])], id[A]);
ans += DIST(cur, m[i][2]) + DIST(m[i][2], m[i][0]);
cur = m[i][0];
}
if (f && d.get(id[A]) == d.get(id[B]))
{
res = min(res, ans + DIST(cur, T));
}
if (!next_permutation(o.begin(), o.end())) break;
}
cout << (res >= inf ? -1 : res) << '\n';
}
