/*
ID: varunra2
LANG: C++
TASK: magic
*/
#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif
#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second
const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions
int n;
VI vals;
VVI adj;
void init() {
vals.resize(n);
adj.resize(n);
}
int ret = 0;
int dfs(int u, int v) {
VI chld;
chld.PB(0);
trav(x, adj[u]) {
if (x == v) continue;
chld.PB(dfs(x, u));
}
if (vals[u] != 1) return 0;
sort(all(chld), greater<int>());
ret = max(ret, chld[0] + 1);
if (sz(chld) == 1) return chld[0] + 1;
ret = max(ret, chld[0] + chld[1] + 1);
return chld[0] + 1;
}
int main() {
// #ifndef ONLINE_JUDGE
// freopen("magic.in", "r", stdin);
// freopen("magic.out", "w", stdout);
// #endif
cin.sync_with_stdio(0);
cin.tie(0);
cin >> n;
init();
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--, v--;
adj[u].PB(v);
adj[v].PB(u);
}
for (int i = 0; i < n; i++) {
cin >> vals[i];
}
int mn = *min_element(all(vals));
if (mn != 1) {
cout << mn << "/1" << '\n';
return 0;
}
dfs(0, -1);
cout << "1/" << ret << '\n';
return 0;
}
