//#pragma GCC optimize(2)
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define N 200005
#define mod 998244353
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define ld long double
#define SZ(x) (int)(x.size())
#define debug cout<<endl<<"ff"<<endl
#define YES cout<<"YES"<<endl
#define NO cout<<"NO"<<endl
#define fi first
#define se second
#define INF 1e9
#define pq priority_queue
#define rep(x,a,b) for(int x=a;x<=b;x++)
int qpow(int a,int b){
	int res=1;
	for(;b;b>>=1){
		if(b&1) res=res*a%mod;
		a=a*a%mod;
	}
	return res;
}
/*int fac[N],ifac[N];
int C(int n,int m){
	if(m>n||m<0||n<0) return 0;
	return fac[n]*ifac[n-m]%mod*ifac[m]%mod;
}
void init(){
	fac[0]=1;
	for(int i=1;i<N;i++) fac[i]=fac[i-1]*i%mod;
	ifac[N-1]=qpow(fac[N-1],mod-2);
	for(int i=N-2;i>=0;i--) ifac[i]=ifac[i+1]*(i+1)%mod;
}*/
/*struct node{
	int nxt,to;
}e[N<<1];
int cnt=1,head[N];
inline void add(int x,int y){
	e[++cnt].nxt=head[x];
	head[x]=cnt;
	e[cnt].to=y;
}*/
inline int lowbit(int x){return x&(-x);}
inline int read(){
  int x=0,t=1;char ch=getchar();
  while(ch<'0'||ch>'9'){
    if(ch=='-') t=-1;
    ch=getchar();
  }
    while(ch>='0'&&ch<='9'){
        x=(x<<1)+(x<<3)+(ch-'0');
        ch=getchar();
    }
    return x*t;
}
inline void write(int x){
	if(x<0) putchar('-'),x=-x;
	if(x>=10) write(x/10);
	putchar(x%10+'0');
}
int dp[N],T,n,col[N][2],c[N],dis[N],dfn[N],dep[N],sz[N],st[20][N],cnt,num,p[N],Rt[N];
struct node{int tag,ls,rs;}tr[N*190];
vector<int>g[N];
int cmp(int x,int y){return dis[x]<dis[y];}
void dfs(int x,int fa){
	sz[x]=1;dep[x]=dep[fa]+1;st[0][x]=fa;dfn[x]=++cnt;
	for(auto t:g[x]){
		if(t==fa) continue;
		dfs(t,x);sz[x]+=sz[t];
	}
}
int LCA(int x,int y){
	if(dep[x]<dep[y]) swap(x,y);
	for(int i=19;i>=0;i--)
		if(dep[st[i][x]]>=dep[y]) 
			x=st[i][x];
	if(x==y) return x;
	for(int i=19;i>=0;i--)
		if(st[i][x]!=st[i][y])
			x=st[i][x],y=st[i][y];
	return st[0][x];
}
void changey(int &rt,int l,int r,int x,int y,int w){
	if(!rt) rt=++num;
	if(x<=l&&r<=y){
		tr[rt].tag=max(tr[rt].tag,w);
		return;
	}
	int mid=(l+r)>>1;
	if(x<=mid) changey(tr[rt].ls,l,mid,x,y,w);
	if(y>mid) changey(tr[rt].rs,mid+1,r,x,y,w);
}
void changex(int rt,int l,int r,int lx,int rx,int ly,int ry,int w){
	if(lx<=l&&r<=rx){
		changey(Rt[rt],1,n,ly,ry,w);
		return;
	}
	int mid=(l+r)>>1;
	if(lx<=mid) changex((rt<<1),l,mid,lx,rx,ly,ry,w);
	if(rx>mid) changex(((rt<<1)|1),mid+1,r,lx,rx,ly,ry,w);
}
int queryy(int rt,int l,int r,int y){
	if(!rt) return 0;
	if(l==r) return tr[rt].tag;
	int res=tr[rt].tag,mid=(l+r)>>1;
	if(y<=mid) res=max(res,queryy(tr[rt].ls,l,mid,y));
	else res=max(res,queryy(tr[rt].rs,mid+1,r,y));
	return res;
}
int queryx(int rt,int l,int r,int x,int y){
	if(!rt) return 0;
	if(l==r) return queryy(Rt[rt],1,n,y);
	int res=queryy(Rt[rt],1,n,y),mid=(l+r)>>1;
	if(x<=mid) res=max(res,queryx((rt<<1),l,mid,x,y));
	else res=max(res,queryx(((rt<<1)|1),mid+1,r,x,y));
	return res;
} 
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>c[i];
		if(col[c[i]][0]) col[c[i]][1]=i;
		else col[c[i]][0]=i;
	}
	for(int i=1;i<n;i++){
		int x,y;cin>>x>>y;
		g[x].pb(y);g[y].pb(x);
	}
	dfs(1,0);
	for(int i=1;i<=n;i++){
		if(col[i][1]==0) dis[i]=0;
		else dis[i]=dep[col[i][0]]+dep[col[i][1]]-2*dep[LCA(col[i][0],col[i][1])];
		p[i]=i;
	}
	int ans=1;
	sort(p+1,p+n+1,cmp);
	for(int i=1;i<=n;i++){
		int x=p[i];
		if(!col[x][1]) continue;
		dp[x]=2;if(st[0][col[x][0]]!=col[x][1]&&st[0][col[x][1]]!=col[x][0]) dp[x]++;
		if(dep[col[x][0]]<dep[col[x][1]]) swap(col[x][0],col[x][1]);
		int L=col[x][0],R=col[x][1];
		dp[x]=max(dp[x],max(queryx(1,1,n,dfn[L],dfn[R]),queryx(1,1,n,dfn[R],dfn[L]))+2);
		ans=max(ans,dp[x]);
		//R是L祖先 
	//	cout<<x<<"+"<<dp[x]<<endl;
		if(dfn[col[x][1]]<=dfn[col[x][0]]&&dfn[col[x][1]]+sz[col[x][1]]-1>=dfn[col[x][0]]){
			int now=L;
			for(int j=19;j>=0;j--)
				if(dep[st[j][now]]>dep[R])
					now=st[j][now];
			R=now;
			if(dfn[R]!=1) changex(1,1,n,dfn[L],dfn[L]+sz[L]-1,1,dfn[R]-1,dp[x]);
			if(dfn[R]+sz[R]<=n) changex(1,1,n,dfn[L],dfn[L]+sz[L]-1,dfn[R]+sz[R],n,dp[x]);
		}else{changex(1,1,n,dfn[L],dfn[L]+sz[L]-1,dfn[R],dfn[R]+sz[R]-1,dp[x]);}
	} 
	cout<<ans<<endl;
	return 0;
}