#include<cstdio>

#include<cstring>

#include<algorithm>

#define read(x) x=getint()

using namespace std;

const int N=20003;

inline const int max( const int &a, const int &b) {return a>b?a:b;}

inline const int getint() { int r=0, k=1; char c=getchar(); for(; c<'0'||c>'9'; c=getchar()) if(c=='-') k=-1; for(; c>='0'&&c<='9'; c=getchar()) r=r*10+c-'0'; return k*r; }

struct node {

    int nxt, to, w;

} E[N<<1];

int point[N], size[N], ma[N], n, cnt=0, rt=0, ans=0, table[N], tn, di[N];

bool vis[N];

inline void insect( int x, int y, int z) {

    cnt++;

    E[cnt].nxt = point[x];

    E[cnt].to = y;

    E[cnt].w = z;

    point[x] = cnt;

}

inline void fdrt( int x, int fa, int s) {

    size[x] = 1;

    ma[x] = 0;

    for( int tmp = point[x]; tmp; tmp = E[tmp].nxt)

        if ( !vis[E[tmp].to] && E[tmp].to != fa) {

            fdrt( E[tmp].to, x, s);

            size[x] += size[E[tmp].to];

            ma[x] = max( ma[x], size[E[tmp].to]);

        }

    if ( s - ma[x] > ma[x])

        ma[x] = s - ma[x];

    if ( ma[x] < ma[rt])

        rt = x;

}

inline void mktb( int x, int fa) {

    table[ ++tn] = di[x];

    for( int tmp = point[x]; tmp; tmp = E[tmp].nxt)

        if ( !vis[E[tmp].to] && E[tmp].to != fa) {

            di[E[tmp].to] = di[x] + E[tmp].w;

            mktb( E[tmp].to, x);

        }

}

inline int work( int x, int beg) {

    int cn0 = 0, cn1 = 0, cn2 = 0;

    tn = 0;

    di[x] = beg;

    mktb( x, -1);

    for( int i = 1; i <= tn; ++i) {

        switch ( table[i] % 3) {

            case 0:

                ++cn0;

            break;

            case 1:

                ++cn1;

            break;

            case 2:

                ++cn2;

            break;

        }

    }

    return cn0 * cn0 + ( ( cn1 * cn2) << 1);

}

inline void dfs( int x, int s) {

    vis[x] = 1;

    ans += work( x, 0);

    for( int tmp = point[x], ss; tmp; tmp = E[tmp].nxt)

        if ( !vis[E[tmp].to]) {

            ans -= work( E[tmp].to, E[tmp].w);

            if ( size[E[tmp].to] > size[x])

                ss = s - size[x];

            else

                ss = size[E[tmp].to];

            rt = 0;

            fdrt( E[tmp].to, x, ss);

            dfs( rt, ss);

        }

}

inline int gcd( int x, int y) {

    int r = x % y;

    while ( r) {

        x = y;

        y = r;

        r = x % y;

    }

    return y;

}

int main() {

    read( n);

    int u, v, e;

    for( int i = 1; i < n; ++i) {

        read( u);

        read( v);

        read( e);

        e %= 3;

        insect( u, v, e);

        insect( v, u, e);

    }

    ma[0] = n+3;

    memset( vis, 0, sizeof(vis));

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

    dfs( rt, n);

    int m = n * n, tong = gcd( ans, m);

    printf( "%d/%d\n", ans / tong, m / tong);

    return 0;

}