#include <bits/stdc++.h>
#define sz(x) ((int)x.size())
#define pii pair<int, int>
#define ft first
#define sd second
#define all(x) x.begin(),x.end()
using namespace std;
typedef long double ld;
typedef long long ll;
const int N = 1000100;
const ll OO = 1e18;
const int oo = 2e9;
vector<int> g[N];
int n, mn, a[N], ansp, ansq, mx[N], mx1[N], mx2[N];
bool smaller(int p, int q){
return ll(p) * ll(ansq) < ll(ansp) * ll(q);
}
void dfs(int v, int p){
mx1[v] = mx2[v] = 0;
for (int u : g[v]){
if (u == p) continue;
dfs(u, v);
if (mx1[v] < mx[u]){
mx2[v] = mx1[v];
mx1[v] = mx[u];
} else if (mx2[v] < mx[u])
mx2[v] = mx[u];
}
if (a[v] == 1)
mx[v] = mx1[v] + 1;
else mx[v] = 0;
}
void DFS(int v, int p, int cr){
for (int u : g[v]){
if (u == p) continue;
int Cr = 0;
if (a[v] == 1) {
if (mx[u] == mx1[v])
Cr = max(cr + 1, mx2[v] + 1);
else Cr = max(cr + 1, mx1[v] + 1);
}
DFS(u, v, Cr);
}
int Mx1 = mx1[v], Mx2 = mx2[v];
if (Mx1 < cr){
Mx2 = Mx1;
Mx1 = cr;
} else if (Mx2 < cr)
Mx2 = cr;
if (smaller(a[v], Mx1 + Mx2 + 1)){
ansp = a[v];
ansq = Mx1 + Mx2 + 1;
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
cin >> n;
for (int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
u--; v--;
g[v].push_back(u);
g[u].push_back(v);
}
mn = oo;
for (int i = 0; i < n; i++){
cin >> a[i];
mn = min(mn, a[i]);
}
if (mn > 1){
cout << mn << "/1";
return 0;
}
ansp = ansq = 1;
dfs(0, -1);
DFS(0, -1, 0);
int gc = __gcd(ansp, ansq);
cout << ansp / gc << "/" << ansq / gc << '\n';
return 0;
}
