/*
_.-- ,.--.
.' .' /
@ |'..--------._
/ \._/ '.
/ .-.- \
( / \ \
\\ '. | #
\\ \ -. /
:\ | )._____.' \
" | / \ | \ )
| |./' :__ \.-'
'--'
*/
#include<bits/stdc++.h>
#define ll long long
#define llll pair<ll,ll>
#define ii pair<int,int>
#define fi first
#define se second
#define FOR(i,l,r) for(int i=l;i<=r;i++)
#define FOD(i,r,l) for(int i=r;i>=l;i--)
#define ull unsigned long long
#define iii pair<int,ii>
#define iv pair<pii,ii>
#define db double
#define ld long double
#define pb push_back
#define tdk "kfph"
using namespace std;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int dxx[] = {1, 1, -1, -1, 2, 2, -2, -2};
const int dyy[] = {2, -2, 2, -2, 1, -1, 1, -1};
const ll INF=1e18;
const int N=1e6+5;
ll dp[20][1<<20],Lock[N];
int n,s,t,h[N],key[N],target[N],cnt,m,tin[N],tout[N];
vector<ii> a[N],LCK;
int K,LG,times;
vector<pair<ii,int>> lks;
ii ST[21][N*2];
void dfs(int u,int par)
{
LCK.pb({h[u],u});
tin[u]=times++;
for(int i=0;i<a[u].size();i++)
{
int v=a[u][i].fi,w=a[u][i].se;
if(v==par) continue;
Lock[v]=(Lock[u]^w);
h[v]=h[u]+1;
dfs(v,u);
LCK.pb({h[u],u});
}
tout[u]=times++;
}
void prepare()
{
LG=__lg(LCK.size());
for(int i=0;i<LCK.size();i++)
{
ST[0][i]=LCK[i];
// cout << LCK[i].fi << ' ' << LCK[i].se <<'\n';
}
for(int i=1;i<=LG;i++)
{
for(int j=0;j+(1<<i)-1<LCK.size();j++)
{
ST[i][j]=min(ST[i-1][j],ST[i-1][j+(1<<(i-1))]);
}
}
}
int lca(int u,int v)
{
if(tin[u]>tin[v]) swap(u,v);
int L=__lg(tin[v]-tin[u]+1);
return min(ST[L][tin[u]],ST[L][tin[v]-(1<<L)+1]).se;
}
int dist(int u,int v)
{
return h[u]+h[v]-2*h[lca(u,v)];
}
bool cango(int u,int v,int mask)
{
int msk=(Lock[u]^Lock[v]);
return ((msk&mask)==msk);
}
void kfph()
{
cin >> n >> s >> t;
for(int i=1;i<n;i++)
{
int u,v,H;
cin >> u >> v >> H;
if(H)
{
a[u].pb({v,1<<cnt});
a[v].pb({u,1<<cnt});
lks.pb({{u,v},H});
cnt++;
}
else
{
a[u].pb({v,0});
a[v].pb({u,0});
}
}
m=cnt;
dfs(s,-1);
K=LCK.size();
prepare();
for(int i=0;i<m;i++)
{
int u=lks[i].fi.fi,v=lks[i].fi.se,k=lks[i].se;
key[i]=k;
if(dist(u,s)>dist(v,s))
{
target[i]=v;
}
else target[i]=u;
}
for(int i=0;i<m;i++)
{
for(int j=0;j<1<<m;j++)
{
dp[i][j]=INF;
}
}
if(cango(s,t,0))
{
cout << dist(s,t);
return;
}
for(int i=0;i<m;i++)
{
if(cango(s,key[i],0) and cango(key[i],target[i],0))
{
dp[i][1<<i]=dist(s,key[i])+dist(key[i],target[i]);
}
}
ll ans=INF;
for(int mask=0;mask<(1<<m);mask++)
{
vector<int> on,off;
for(int j=0;j<m;j++)
{
if((mask>>j)&1)
{
on.pb(j);
}
else off.pb(j);
}
for(int i:on)
{
if(dp[i][mask]==INF) continue;
if(cango(target[i],t,mask)) ans=min(ans,dp[i][mask]+dist(target[i],t));
for(int j:off)
{
if(cango(target[i],key[j],mask) and cango(key[j],target[j],mask))
{
dp[j][(mask|(1<<j))]=min(dp[j][(mask|(1<<j))],dp[i][mask]+dist(target[i],key[j])+dist(key[j],target[j]));
}
}
}
}
if(ans==INF) ans=-1;
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
if(fopen(tdk".inp","r"))
{
freopen(tdk".inp","r",stdin);
freopen(tdk".out","w",stdout);
}
int t=1;
// cin >> t;
while(t--)
{
kfph();
}
return 0;
}
