#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define rg register
#define il inline
#define mp make_pair
#define rp(i,x,y) for(rg ll i=x;i<=y;++i)

const ll N=200000+10;
ll n,m,head[N],cnt,f[N][3],g[3],as1,as2;
struct ed{ll to,nxt,wei;}edge[N<<2];
bool vis[N];

il ll read()
{
    rg char ch=getchar();rg ll x=0;rg bool y=1;
    while(ch!='-' && (ch>'9' || ch<'0'))ch=getchar();
    if(ch=='-')ch=getchar(),y=0;
    while(ch>='0' && ch<='9')x=(x<<1)+(x<<3)+(ch^'0'),ch=getchar();
    return y?x:-x;
}
il ll gcd(ll x,ll y){return y==0?x:gcd(y,x%y);}
il void ad(ll x,ll y,ll z){edge[++cnt].to=y;edge[cnt].nxt=head[x];edge[cnt].wei=z;head[x]=cnt;}
void dfs(ll nw)
{
    vis[nw]=1;f[nw][0]=1;
    for(rg ll i=head[nw];i;i=edge[i].nxt)
    {
        if(vis[edge[i].to])continue;dfs(edge[i].to);
        rp(j,0,2)g[(edge[i].wei+j)%3]=f[edge[i].to][j];
        rp(j,0,2)as1+=(ll)g[j]*f[nw][(3-j)%3];
        rp(j,0,2)f[nw][j]+=g[j];
    }
}

int main()
{
    n=read();rp(i,1,n-1){ll x=read(),y=read(),z=read();ad(x,y,z);ad(y,x,z);}
    dfs(1);as1<<=1;as1+=n;as2=(ll)n*n;ll tmp=gcd(as1,as2);as1/=tmp;as2/=tmp;printf("%lld/%lld\n",as1,as2);
    return 0;
}