//by szh
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pb push_back
#define debug(x) cerr<<#x<<"="<<x<<endl
#define pq priority_queue
#define inf 0x3f
#define rep(i,a,b) for (int i=a;i<(b);i++)
#define MP make_pair
#define SZ(x) (int(x.size()))
#define ll long long
#define mod 1000000007
#define ALL(x) x.begin(),x.end()
void inc(int &a,int b) {a=(a+b)%mod;}
void dec(int &a,int b) {a=(a-b+mod)%mod;}
int lowbit(int x) {return x&(-x);}
ll p0w(ll base,ll p) {ll ret=1;while(p>0){if (p%2ll==1ll) ret=ret*base%mod;base=base*base%mod;p/=2ll;}return ret;}
#include "catdog.h"
int x;
const int maxn = 1010;
int dp[3][maxn];
int state[maxn];
vector <int> edge[maxn];
void initialize(int N, std::vector<int> A, std::vector<int> B) {
rep(i,0,N-1) edge[A[i]].pb(B[i]), edge[B[i]].pb(A[i]);
}
void dfs(int u,int fa) {
if (state[u]!=0) {
int &ans = dp[state[u]][u];
ans = 0;
for (int v:edge[u]) {
if (fa==v) continue;
dfs(v,u);
ans += min(dp[0][v],min(dp[state[u]][v],dp[3-state[u]][v]+1));
ans = min(ans,mod);
}
}
else {
rep(i,0,3) dp[i][u] = 0;
for (int v:edge[u]) {
if (fa==v) continue;
dfs(v,u);
dp[0][u] += min(dp[0][v],min(dp[1][v],dp[2][v])+1);
dp[1][u] += min(dp[0][v],min(dp[1][v],dp[2][v]+1));
dp[2][u] += min(dp[0][v],min(dp[1][v]+1,dp[2][v]));
rep(j,0,3) dp[j][u] = min(dp[j][u],mod);
}
}
return;
}
int solve() {
memset(dp,inf,sizeof(dp));
dfs(1,-1);
return min(dp[0][1],min(dp[1][1],dp[2][1]));
}
int cat(int v) {
state[v] = 1;
return solve();
}
int dog(int v) {
state[v] = 2;
return solve();
}
int neighbor(int v) {
state[v] = 0;
return solve();
}
