#include<bits/stdc++.h>
#define int ll
#define lc (rt<<1)
#define rc (rt<<1)
#define mid (l+r>>1)
#define rg register
#define pb push_back
#define ppb pop_back
#define mkp make_pair
#define DEBUG printf("Debug on line %d\n", __LINE__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
const int N = 50;
const int INF = 0x3f3f3f3f;
inline int read(){
int n=0, f=1; char ch = getchar();
for(; !isdigit(ch); ch=getchar()) if(ch == '-') f=-1;
for(; isdigit(ch); ch=getchar()) n=n*10+ch-'0';
return n*f;
}
int n, ans=INF;
bitset<N> a[N], s, ze;
unordered_map<bitset<N>, int> mp;
void dfs1(bitset<N> cur, int step, int i){
if(!mp.count(cur)) mp[cur] = step;
else mp[cur] = min(mp[cur], step);
// cout << step << ' ' << cur << endl;
for(; i<=(n>>1); i++){
dfs1(cur^a[i], step+1, i+1);
}
}
void dfs2(bitset<N> cur, int step, int i){
// cout << 2 << ' ' << cur << endl;
if(mp.count(cur)){
ans = min(ans, mp[cur]+step);
// cout << cur << endl;
// printf("%lld %lld\n", mp[cur], step);
}
for(; i<=n; i++){
dfs2(cur^a[i], step+1, i+1);
}
}
signed main(){
n = read();
for(int i=1; i<n; i++){
int u = read(), v = read();
a[u] |= (1<<(v-1));
a[v] |= (1<<(u-1));
}
for(int i=1; i<=n; i++){
a[i] |= (1<<(i-1));
// cout << a[i] << endl;
}
for(int i=0; i<n; i++){
s |= (read() << i);
}
dfs1(s, 0, 1);
dfs2(ze, 0, (n>>1)+1);
printf("%lld\n", ans);
}
