#include<cstdio>
#include<algorithm>
#include<cstring>
#define N 20005
typedef long long ll;
using namespace std;
ll n,K,fa[N],sze[N],son[N],dis[N],head[N],ecnt,ans,tot;
bool vis[N];
struct edge {ll nxt,v,w;}e[2*N];
ll gcd(ll x,ll y) { return y==0?x:gcd(y,x%y);}
void add(ll u,ll v,ll w)
{
e[++ecnt].v=v,e[ecnt].w=w,e[ecnt].nxt=head[u],head[u]=ecnt;
e[++ecnt].v=u,e[ecnt].w=w,e[ecnt].nxt=head[v],head[v]=ecnt;
}
int calcG(int sv)
{
static int qn,que[N];
int u,v,mx=n,G;
que[qn=1]=sv,fa[sv]=0;
for (int ql=1;ql<=qn;ql++)
{
sze[u=que[ql]]=1,son[u]=0;
for (int i=head[u];i;i=e[i].nxt)
{
if (vis[v=e[i].v] || v==fa[u]) continue;
fa[v]=u,que[++qn]=v;
}
}
for (int ql=qn;ql>=1;ql--)
{
u=que[ql],v=fa[u];
if (qn-sze[u]>son[u]) son[u]=qn-sze[u];
if (son[u]<mx) G=u,mx=son[u];
if (!v) break;
sze[v]+=sze[u];
if (sze[u]>son[v]) son[v]=sze[u];
}
return G;
}
inline ll calc(int sv,ll L)
{
static int qn,que[N];
int cnt[4],u,v;
memset(cnt,0,sizeof(cnt));
que[qn=1]=sv,dis[sv]=L,fa[sv]=0;
for (int ql=1;ql<=qn;ql++)
{
cnt[dis[u=que[ql]]%3]++;
for (int i=head[u];i;i=e[i].nxt)
if (vis[v=e[i].v] || v==fa[u]) continue ;
else fa[v]=u,dis[v]=dis[u]+e[i].w,que[++qn]=v;
}
return cnt[0]*cnt[0]+cnt[1]*cnt[2]*2;
}
void solve(int u)
{
int G=calcG(u);
vis[G]=1;
ans+=calc(G,0);
for (int i=head[G];i;i=e[i].nxt)
if (!vis[e[i].v]) ans-=calc(e[i].v,e[i].w);
for (int i=head[G];i;i=e[i].nxt)
if (!vis[e[i].v]) solve(e[i].v);
}
int main()
{
scanf("%lld",&n);
for (ll i=1,u,v,w;i<n;i++)
{
scanf("%lld%lld%lld",&u,&v,&w);
add(u,v,w%3);
}
solve(1);
ll G=gcd(ans,tot=n*n);
printf("%lld/%lld\n",ans/G,tot/G);
return 0;
}