#include<bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define mp make_pair
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
template<typename T,typename U>
T ceil(T x, U y) {return (x>0?(x+y-1)/y:x/y);}
template<typename T,typename U>
T floor(T x, U y) {return (x>0?x/y:(x-y+1)/y);}
template<class T,class S>
bool chmax(T &a,const S b) {return (a<b?a=b,1:0);}
template<class T,class S>
bool chmin(T &a,const S b) {return (a>b?a=b,1:0);}
int popcnt(int x) {return __builtin_popcount(x);}
int popcnt(ll x) {return __builtin_popcountll(x);}
int topbit(int x) {return (x==0?-1:31-__builtin_clz(x));}
int topbit(ll x) {return (x==0?-1:63-__builtin_clzll(x));}
int lowbit(int x) {return (x==0?-1:__builtin_ctz(x));}
int lowbit(ll x) {return (x==0?-1:__builtin_ctzll(x));}

#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

const int N=2e5+5;
int n,id[N],p[N],d[N],fa[N][25],f[N];
vi e[N];

int find(int i) {return i==id[i]?i:id[i]=find(id[i]);}
void dfs(int u,int ft) {
  d[u]=d[ft]+1; fa[u][0]=ft;
  rep(h,1,20) fa[u][h]=fa[fa[u][h-1]][h-1];
  for(int v:e[u]) if(v!=ft) dfs(v,u);
}
int lca(int u,int v) {
  if(d[u]<d[v]) swap(u,v);
  per(h,20,0) if(d[fa[u][h]]>=d[v]) u=fa[u][h];
  per(h,20,0) if(fa[u][h]!=fa[v][h]) u=fa[u][h], v=fa[v][h];
  return u==v?u:fa[u][0];
}
int dis(int u,int v) {
  return d[u]+d[v]-2*d[lca(u,v)];
}

signed main() {
  n=read();
  rep(i,1,n) p[i]=read(), id[i]=i;
  rep(i,2,n) {
    int u=p[read()], v=p[read()];
    e[u].eb(v), e[v].eb(u);
  }
  dfs(n,0);
  rep(u,1,n) {
    for(int v:e[u]) if(v<u) {
      v=find(v);
      f[u]=max(f[u],f[v]+dis(u,v));
      id[v]=u;
    }
  }
  printf("%lld\n",f[n]);
  return 0;
}