// 模板题
#include <bits/stdc++.h>

const int N = 2e4 + ;

int n, now = , head[N], dis[N];

struct Node {int v, w, nxt;} G[N << ];

int size[N], maxson[N], Root;

bool vis[N];

int js[N];

int Answer;

int Size;

#define gc getchar()

inline int read() {

    int x = ; char c = gc;

    while(c < '' || c > '') c = gc;

    while(c >= '' && c <= '') x = x *  + c - '', c = gc;

    return x;

} 

inline void Add(int u, int v, int w) {G[now].v = v; G[now].w = w; G[now].nxt = head[u]; head[u] = now ++;}

void Getroot(int u, int fa) {

    size[u] = ;

    maxson[u] = ;

    for(int i = head[u]; ~ i; i = G[i].nxt) {

        int v = G[i].v;

        if(vis[v] || v == fa) continue ;

        Getroot(v, u);

        size[u] += size[v];

        maxson[u] = std:: max(maxson[u], size[v]);

    }

    maxson[u] = std:: max(maxson[u], Size - size[u]);

    if(maxson[u] < maxson[Root]) Root = u;

}

void Getdis(int u, int fa, int len) {

    dis[u] = len; js[dis[u]] ++;

    for(int i = head[u]; ~ i; i = G[i].nxt) {

        int v = G[i].v;

        if(vis[v] || v == fa) continue ;

        Getdis(v, u, (len + G[i].w) % );

    }

}

int Calc(int u, int len) {

    js[] = js[] = js[] = ;

    Getdis(u, , len % );

    return js[] * js[] *  + js[] * js[];

}

void Getans(int u) {

    vis[u] = ;

    Answer += Calc(u, );

//    std:: cout << "#";

//    for(int i = 1; i <= n; i ++) std:: cout << dis[i] << " ";

//    std:: cout << "\n";

    for(int i = head[u]; ~ i; i = G[i].nxt) {

        int v = G[i].v;

        if(vis[v]) continue ;

        Answer -= Calc(v, G[i].w);

        Root = ;

        Size = size[v];

        Getroot(v, u);

        Getans(Root);

    }

}

int Gcd(int a, int b) {

    return b ==  ? a : Gcd(b, a % b);

}

int main() {

//    freopen("gg.in", "r", stdin);

    n = read();

    for(int i = ; i <= n; i ++) head[i] = -;

    for(int i = ; i < n; i ++) {

        int u = read(), v = read(), w = read();

        Add(u, v, w), Add(v, u, w);

    }

    maxson[Root] = n;

    Size = n;

    Getroot(, );

//    std:: cout << Root << "\n";

    Getans(Root);

    int gcd = Gcd(Answer, n * n);

    std:: cout << Answer / gcd << "/" << n * n / gcd << "\n";

    return ;

}