#include<bits/stdc++.h>
using namespace std;
const int N=200005,H=18,M=36100005;
int n,a[N],c[N],d[N],fa[N][H],dfn[N],dfm[N],idx;
vector<int> e[N];
struct node {
    int x,y,z,d;
    bool operator <(const node &o) const {return d>o.d;}
} b[N];
struct sgt {
    int idx,rt[4*N];
    struct node {int lc,rc,mx;} tr[M];
    void modify2(int x,int v,int &p,int l=1,int r=n) {
        if(!p) p=++idx;
        tr[p].mx=max(tr[p].mx,v);
        if(l==r) return ;
        int mid=l+r>>1;
        if(x<=mid) modify2(x,v,tr[p].lc,l,mid);
        else modify2(x,v,tr[p].rc,mid+1,r);
    }
    void modify(int x,int y,int v,int p=1,int l=1,int r=n) {
        modify2(y,v,rt[p]);
        if(l==r) return ;
        int mid=l+r>>1;
        if(x<=mid) modify(x,y,v,p<<1,l,mid);
        else modify(x,y,v,p<<1|1,mid+1,r);
    }
    int query2(int L,int R,int p,int l=1,int r=n) {
        if(!p) return 0;
        if(L<=l&&r<=R) return tr[p].mx;
        int mid=l+r>>1,res=0;
        if(L<=mid) res=query2(L,R,tr[p].lc,l,mid);
        if(R>mid) res=max(res,query2(L,R,tr[p].rc,mid+1,r));
        return res;
    }
    int query(int L,int R,int L2,int R2,int p=1,int l=1,int r=n) {
        if(L<=l&&r<=R) return query2(L2,R2,rt[p]);
        int mid=l+r>>1,res=0;
        if(L<=mid) res=query(L,R,L2,R2,p<<1,l,mid);
        if(R>mid) res=max(res,query(L,R,L2,R2,p<<1|1,mid+1,r));
        return res;
    }
} tr;
int read() {
	int x=0,f=1; char c=getchar();
	for(;c<'0'||c>'9';c=getchar()) if(c=='-') f=-1;
	for(;c>='0'&&c<='9';c=getchar()) x=x*10+c-48;
	return x*f;
}
void dfs(int x,int Fa) {
    dfn[x]=++idx; d[x]=d[Fa]+1; fa[x][0]=Fa;
    for(int i=1;1<<i<d[x];i++) fa[x][i]=fa[fa[x][i-1]][i-1];
    for(int y:e[x]) if(y!=Fa) dfs(y,x);
    dfm[x]=idx;
}
int lca(int x,int y) {
    if(d[x]<d[y]) swap(x,y);
    if(d[x]>d[y]) for(int c=d[x]-d[y],i=__lg(c);~i;i--) if(c>>i&1) x=fa[x][i];
    if(x==y) return x;
    for(int i=__lg(d[x]);~i;i--) if(fa[x][i]!=fa[y][i]) x=fa[x][i],y=fa[y][i];
    return fa[x][0];
}
int main() {
    n=read();
    for(int i=1;i<=n;i++) a[i]=read();
    for(int i=1;i<n;i++) {
        int x=read(),y=read();
        e[x].push_back(y);
        e[y].push_back(x);
    }
    dfs(1,0);
    for(int i=1;i<=n;i++) (b[a[i]].x?b[a[i]].y:b[a[i]].x)=i;
    for(int i=1;i<=n;i++) if(b[i].x&&b[i].y) {
        b[i].z=lca(b[i].x,b[i].y);
        b[i].d=d[b[i].x]+d[b[i].y]-2*d[b[i].z];
    }
    sort(b+1,b+n+1);
    int ans=1;
    for(int i=1;i<=n&&b[i].d;i++) {
        int x=b[i].x,y=b[i].y,z,res=0;
        if(dfn[x]>dfn[y]) swap(x,y);
        if(b[i].z!=x) res=tr.query(dfn[x],dfm[x],dfn[y],dfm[y])+2;
        else {
            for(int j:e[x]) if(dfn[j]<=dfn[y]&&dfn[y]<=dfm[j]) {z=j; break;}
            if(dfn[z]>1) res=max({res,tr.query(dfn[y],dfm[y],1,dfn[z]-1)+2,tr.query(1,dfn[z]-1,dfn[y],dfm[y])+2});
            if(dfm[z]<n) res=max({res,tr.query(dfn[y],dfm[y],dfm[z]+1,n)+2,tr.query(dfm[z]+1,n,dfn[y],dfm[y])+2});
        }
        tr.modify(dfn[x],dfn[y],res);
        ans=max(ans,res+(b[i].d>1));
    }
    printf("%d\n",ans);
    return 0;
}