#include<bits/stdc++.h>

using namespace std;

#define MAXN 20010

int i,n,u,v,w,ans1,ans2,g,tot,len,root;

int head[MAXN],size[MAXN],weight[MAXN],d[MAXN],sum[MAXN];

bool visited[MAXN];

struct Edge

{

    int to,w,nxt;

} e[MAXN<<];

inline int gcd(int x,int y)

{

    if (y == ) return x;

    else return gcd(y,x % y);

}

inline void addedge(int u,int v,int w)

{

    tot++;

    e[tot] = (Edge){v,w,head[u]};

    head[u] = tot;

}

inline void getroot(int u,int fa,int total)

{

    int i,v;

    size[u] = ;

    weight[u] = ;

    for (i = head[u]; i; i = e[i].nxt)

    {

        v = e[i].to;

        if (v != fa && !visited[v])

        {

            getroot(v,u,total);

            size[u] += size[v];

            weight[u] = max(weight[u],size[v]);

        }

    }

    weight[u] = max(weight[u],total - size[u]);

    if (weight[u] < weight[root]) root = u;

}

inline void dfs(int u,int fa)

{

    int i,v,w;

    d[++len] = sum[u];

    for (i = head[u]; i; i = e[i].nxt)

    {

        v = e[i].to;

        w = e[i].w;

        if (v != fa && !visited[v])

        {

            sum[v] = (sum[u] + w) % ;

            dfs(v,u);

        }

    }

}

inline int calc(int u)

{

    int i;

    int ret = ;

    int cnt[];

    memset(cnt,,sizeof(cnt));

    len = ;

    dfs(u,);

    for (i = ; i <= len; i++) cnt[d[i]]++;

     for (i = ; i <= len; i++) ret += cnt[( - d[i]) % ];

    return ret;

}

inline void work(int u)

{

    int i,v,w;

    visited[u] = true;

    sum[u] = ;

    ans1 += calc(u);

    for (i = head[u]; i; i = e[i].nxt)

    {

        v = e[i].to;

        w = e[i].w;

        if (!visited[v])

        {

            sum[v] = w % ;

            ans1 -= calc(v);

            root = ;

            getroot(v,,size[v]);

            work(root);

        }

    }

}

int main()

{

    scanf("%d",&n);

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

    {

        scanf("%d%d%d",&u,&v,&w);

        addedge(u,v,w);

        addedge(v,u,w);

    }

    memset(visited,false,sizeof(visited));

    size[] = weight[] = n;

    getroot(,,n);

    ans1 = ;

    ans2 = n * n;

    work(root);

    g = gcd(ans1,ans2);

    ans1 /= g; ans2 /= g;

    printf("%d/%d\n",ans1,ans2);

    return ;

}