#include <iostream>
#include <cstring> 
#include <map>
#include <vector>
#include <queue>
#include <cmath>
#include <algorithm>
// #include <map>
// #include <bits/stdc++.h>

// #define int long long
#define For(i,a,b) for(int i=(a);i<=(b);i++)
#define Rof(i,a,b) for(int i=(a);i>=(b);i--)
#define Grf(it,u,to) for(int it=he[u],to;(to=e[it],it);it=nxt[it]) 
#define In __inline 
#define OP operator
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
namespace Mine {
	// mt19937_64 wql(514);
	In ll read() {
		ll x=1,a=0;
		char ch=getchar();
		while(ch>'9' || ch<'0') x=(ch=='-')?-1:x,ch=getchar();
		while(ch>='0' && ch<='9') a=(a<<1)+(a<<3)+(ch-'0'),ch=getchar();
		return a*x;
	} const int N=1e5+100;
	int he[N],e[N<<1],nxt[N<<1]; namespace E {int idx=1;
		void adde(int a,int b){e[++idx]=b,nxt[idx]=he[a];he[a]=idx;}
	}using E::adde; int n,ans,a[N],b[N],root[N],len;
#define lc(u) tr[(u)].lc
#define rc(u) tr[(u)].rc
	In int gmax(int &x,int y){return (x=max(x,y));}struct node {
		int lc,rc,f[2];
	} tr[N*60]; int idx=1; void mdf(int &u,int pos,int val,int op,int l=1,int r=len) {
		if(!u) {u=++idx;} ans=max(ans,gmax(tr[u].f[op],val));
		int mid=(l+r)>>1;if(l==r) return ;
		if(pos<=mid) mdf(tr[u].lc,pos,val,op,l,mid);
		else mdf(tr[u].rc,pos,val,op,mid+1,r);
	} int merge(int x,int y) { if(!x || !y) return x+y;
		gmax(ans,max(tr[lc(x)].f[0]+tr[rc(y)].f[1],tr[lc(y)].f[0]+tr[rc(x)].f[1]));
		gmax(tr[x].f[0],tr[y].f[0]);gmax(tr[x].f[1],tr[y].f[1]);
		lc(x)=merge(lc(x),lc(y)); rc(x)=merge(rc(x),rc(y)); return x;
	} int qry(int u,int ql,int qr,int op,int l=1,int r=len) {
		if(!u) return 0;
		if(ql>qr) return 0;
		if(ql<=l && r<=qr) return tr[u].f[op];
		int mid=(l+r)>>1; if(qr<=mid) return qry(lc(u),ql,qr,op,l,mid);
		if(mid<ql) return qry(rc(u),ql,qr,op,mid+1,r);
		return max(qry(lc(u),ql,qr,op,l,mid),qry(rc(u),ql,qr,op,mid+1,r));
	} void dfs(int u,int fa) {
		 int mx1=0,mx0=0;Grf(it,u,to) { if(to==fa) continue;
			dfs(to,u); int t0=qry(root[to],1,a[u]-1,0),t1=qry(root[to],a[u]+1,len,1);
			gmax(ans,max(mx1+t0,mx0+t1)+1);gmax(mx0,t0);gmax(mx1,t1);
			root[u]=merge(root[u],root[to]);
		} mdf(root[u],a[u],mx0+1,0); mdf(root[u],a[u],mx1+1,1);
		// printf("%d :",u); print(root[u]);puts("");
	} signed main() {n=read(); For(i,1,n) {a[i]=b[i]=read();} sort(b+1,b+1+n);
		len=unique(b+1,b+1+n)-b-1; For(i,1,n) {a[i]=lower_bound(b+1,b+1+n,a[i])-b;}
		For(i,1,n-1) {int a=read(),b=read();adde(a,b);adde(b,a);}
		dfs(1,0); 
		return printf("%d",ans) , 0;
	}
}signed main() {
	// freopen("homework.in","r",stdin);
	// freopen("homework.out","w",stdout);
	return Mine::main();
}