#include <bits/stdc++.h>
using namespace std;
const int N = 2e4 + 4;
vector< pair<int, int> > G[N];
int n, ans;
int siz[N], all, rt, rtmaxsiz;
int dis[N], t[4];
bool del[N];

void getroot(int x, int xfa)
{
    siz[x] = 1;
    int xmaxsiz = 0;
    for (auto i:G[x])
        if (i.first != xfa && !del[i.first]){
            getroot(i.first, x);
            siz[x] += siz[i.first];
            xmaxsiz = max(xmaxsiz, siz[i.first]);
        }
    xmaxsiz = max(xmaxsiz, all - siz[x]);
    if (xmaxsiz < rtmaxsiz) rtmaxsiz = xmaxsiz, rt = x;
}

void getdis(int x, int xfa)
{
    t[dis[x]]++;
    for (auto i:G[x])
        if (i.first != xfa && !del[i.first]){
            dis[i.first] = (dis[x] + i.second)%3;
            getdis(i.first, x);
        }
}

int calc(int x,int w)
{
    t[0]=t[1]=t[2]=0;
    dis[x]=w;
    getdis(x, 0);
    return t[1]*t[2]*2 + t[0]*t[0];
}

void divide(int x)
{
    ans+=calc(x,0);
    del[x] = true;
    for (auto i:G[x])
        if (!del[i.first]){
            ans-=calc(i.first,i.second);
            all=rtmaxsiz=siz[i.first];getroot(i.first, x);getroot(rt, x);
            divide(rt);
        }
}
int gcd(int a,int b){ return b==0?a:gcd(b,a%b);}
int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cin >> n ;
    for (int i = 2, x, y, w; i <= n; i++)
    {
        cin >> x >> y >> w; w%=3;
        G[x].push_back({y, w});
        G[y].push_back({x, w});
    }

    ans = 0;

    all=rtmaxsiz=n;getroot(1, 0);getroot(rt, 0);
    divide(rt);

    int g= gcd(ans,n*n);

    cout << ans/g << "/" << n*n/g << "\n"  ;
    return 0;
}