#include <bits/stdc++.h>
#define endl "\n"
using namespace std ;
typedef long long ll;
typedef long double ld ;
const int N=2e7;
const ll inf=1e18 ;
const ll mod = 1e9 + 7 ;
ll mypower(ll x, ll y){
if(y == 0) return 1 ;
if(y == 1) return x ;
ll ret = mypower(x , y / 2);
ret = (ret * ret) % mod;
if(y % 2) ret = ( ret * x ) % mod ;
return ret ;
}
ll dp1[1000006] , dp2[1000006] , n , a[1000006] ;
vector < ll > v[1000006] ;
void update(ll node , ll x){
dp2[node] = max(dp2[node] , x) ;
if(dp1[node] < dp2[node]){
swap(dp1[node] , dp2[node]) ;
}
return ;
}
void dfs(ll node, ll par){
for (auto p : v[node]){
if (p == par) continue;
dfs(p , node);
if (a[p] == 1) update(node, dp1[p] + 1);
}
}
void dfs1(ll node , ll par){
for (auto p : v[node]){
if (p == par) continue;
if (a[node] == 1){
if ((dp1[p] + 1) == dp1[node]) update(p , dp2[node] + 1) ;
else update(p, dp1[node] + 1) ;
}
dfs1(p , node) ;
}
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n ;
for(int i = 1 ; i < n ; i ++){
ll x , y ;
cin >> x >> y ;
v[x].push_back(y) ;
v[y].push_back(x) ;
}
for(int i = 1 ; i <= n ; i++){
cin >> a[i] ;
}
dfs(1 , 1) ;
dfs1(1 ,1) ;
pair < ll , ll > ans = {1e18 , 1} ;
for(int i = 1 ; i <= n; i++){
if(a[i] * ans.second < ans.first *(dp1[i] + dp2[i] + 1))
ans = {a[i] , dp1[i] + dp2[i] + 1} ;
}
ll q = __gcd(ans.first , ans.second) ;
ans.first /= q ;
ans.second /= q ;
cout << ans.first << "/" << ans.second << endl ;
return 0 ;
}
