/*
Code by @marlov
*/
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <utility>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <stack>
#include <queue>
#include <iterator>
using namespace std;
typedef long long ll;
typedef pair<long long,long long> pi;
#define maxN 1000005
#define INF 2000000000
long long N;
vector<long long> adj[maxN];
long long magic[maxN];
long long dp1[maxN];
long long f1[maxN];
long long dp2[maxN];
long long f2[maxN];
long long tmv=INF;
long long top=1;
long long bottom=1;
void na(long long t,long long b){
if(t*bottom<top*b){
top=t;
bottom=b;
}
}
void dfsbu(long long n,long long p){
for(long long i:adj[n]) if(i!=p){
dfsbu(i,n);
}
if(magic[n]>2) return;
for(long long i:adj[n]) if(i!=p){
if(magic[i]==1){
if(dp1[i]>=dp1[n]){
dp2[n]=dp1[n];
f2[n]=f1[n];
dp1[n]=dp1[i]+1;
f1[n]=i;
}else if(dp2[i]>=dp2[n]){
dp2[n]=dp2[i]+1;
f2[n]=i;
}
}
}
}
void dfsud(long long n,long long p){
if(magic[n]<3&&n!=0&&magic[p]==1){
if(f1[p]!=n){
if(dp1[p]>=dp1[n]){
dp2[n]=dp1[n];
f2[n]=f1[n];
dp1[n]=dp1[p]+1;
f1[n]=p;
}
}else if(f2[p]!=n){
if(dp2[p]>=dp1[n]){
dp2[n]=dp1[n];
f2[n]=f1[n];
dp1[n]=dp2[p]+1;
f1[n]=p;
}else if(dp2[p]>=dp2[n]){
dp2[n]=dp2[p]+1;
f2[n]=p;
}
}
}
for(long long i:adj[n]) if(i!=p){
dfsud(i,n);
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>N;
long long u,v;
for(long long i=0;i<N-1;i++){
cin>>u>>v;
u--;v--;
adj[u].push_back(v);
adj[v].push_back(u);
}
for(long long i=0;i<N;i++){
cin>>magic[i];
tmv=min(tmv,magic[i]);
f1[i]=-1;
f2[i]=-1;
dp1[i]=0;
dp2[i]=0;
//if(magic[i]==1) dp1[i]=1;
}
if(tmv>1){
cout<<tmv<<"/"<<1<<'\n';
return 0;
}
dfsbu(0,-1);
dfsud(0,-1);
for(long long i=0;i<N;i++){
if(magic[i]==2&&dp1[i]==dp2[i]){
na(2,(dp1[i]+dp2[i]+1));
}else if(magic[i]==1){
na(1,(dp1[i]+dp2[i]+1));
}
}
if(top==2&&bottom%2==0){
cout<<top/2<<"/"<<bottom/2<<'\n';
}else{
cout<<top<<"/"<<bottom<<'\n';
return 0;
}
/* stuff you should look for
* long long overflow, array bounds
* special cases (n=1,n=0?)
* do smth instead of nothing and stay organized
*/
Compilation message
mag.cpp: In function 'int main()':
mag.cpp:134:1: error: expected '}' at end of input
134 | }
| ^
mag.cpp:96:12: note: to match this '{'
96 | int main() {
| ^
