/*=================================

# Created time: 2016-04-20 14:35

# Filename: 2152.cpp

# Description:

=================================*/

#define me AcrossTheSky&HalfSummer11

#include <cstdio>

#include <cmath>

#include <ctime>

#include <string>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>  

#include <set>

#include <stack>

#include <queue>

#include <vector>  

#define lowbit(x) (x)&(-x)

#define Abs(x) ((x) > 0 ? (x) : (-(x)))

#define FOR(i,a,b) for((i)=(a);(i)<=(b);(i)++)

#define FORP(i,a,b) for(int i=(a);i<=(b);i++)

#define FORM(i,a,b) for(int i=(a);i>=(b);i--)

#define ls(a,b) (((a)+(b)) << 1)

#define rs(a,b) (((a)+(b)) >> 1)

#define getlc(a) ch[(a)][0]

#define getrc(a) ch[(a)][1]  

#define maxn 100005

#define maxm 100005

#define INF 1070000000

using namespace std;

typedef long long ll;

typedef unsigned long long ull;  

template<class T> inline

void read(T& num){

    num = 0; bool f = true;char ch = getchar();

    while(ch < '0' || ch > '9') { if(ch == '-') f = false;ch = getchar();}

    while(ch >= '0' && ch <= '9') {num = num * 10 + ch - '0';ch = getchar();}

    num = f ? num: -num;

}

int outs[100];

template<class T> inline

void write(T x){

	if (x==0) {putchar('0'); putchar(' '); return;}

	if (x<0) {putchar('-'); x=-x;}

	int num=0;

	while (x){ outs[num++]=(x%10); x=x/10;}

	FORM(i,num-1,0) putchar(outs[i]+'0');

}

/*==================split line==================*/

int n,m,mn,root,cnt,ans,sume=0;

bool vis[maxn];

struct Edge{int to,next,w;} e[maxm];

int first[maxn],sz[maxn],dep[maxn],d[maxn];

inline int gcd(int a,int b) { return b==0?a:gcd(b,a%b);}

inline void addedge(int x,int y,int w){

	sume++; e[sume].to=y; e[sume].w=w;e[sume].next=first[x]; first[x]=sume;

}

inline int getroot(int x,int fa,int sum){

	sz[x]=1; int mx=0,y; //`vis[x]=true;

	for (int i = first[x];i;i=e[i].next)

	if (!vis[y=e[i].to] && e[i].to!=fa){

		getroot(y,x,sum);

		sz[x]+=sz[y];

		mx=max(mx,sz[y]);

	}

	mx=max(mx,sum-mx);

	if (mx<mn) mn=mx,root=x;

}

inline void getdep(int x,int fa){

	dep[++cnt]=d[x]; int y;

	for (int i=first[x];i;i=e[i].next)

		if (!vis[y=e[i].to] && e[i].to!=fa){

			d[y]=d[x]+e[i].w;

			getdep(y,x);

		}

}

inline int cal(int x,int last=0){

	int c[3]; memset(c,0,sizeof(c));

	cnt=0; d[x]=last;

	getdep(x,-1);

	FORP(i,1,cnt) c[dep[i]%3]++;

	return c[0]*c[0]+(c[1]*c[2])*2;

}

inline void dfs(int x,int sum){

	vis[x]=true;

	ans+=cal(x); int y;

	for (int i=first[x];i;i=e[i].next) if (!vis[y=e[i].to]){

		ans-=cal(y,e[i].w);

		int s=sz[y]>sz[x]?sum-sz[x]:sz[y];

		root=0; mn=INF; getroot(y,x,s);

		dfs(root,s);

	}

}

int main(){

	read(n);

	FORP(i,1,n-1) {

		int x,y,z; read(x); read(y); read(z);

		addedge(x,y,z%3); addedge(y,x,z%3);

	}

	memset(vis,false,sizeof(vis));

	mn=INF;

	getroot((n+1)>>1,-1,n);

	dfs(root,n);

	int down=n*n,t=gcd(ans,down);

	write(ans/t); putchar('/'); write(down/t); puts("");

}