#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define rep(a,b) for(int a = 0; a < (b); ++a)
#define all(t) t.begin(), t.end()
#define pb push_back
const int N = 5e5+5, LG = 18, INF = 2e9+54321;
const ll INF_L = (ll)2e18+54321;
struct Node
{
int v, val;
bool operator < (const Node &node) const
{
return val < node.val;
}
};
int n,cnt,base,rozmiar_drzewa;
int A[N];
vector<int> G[N];
bool vis[N];
int pre[N];
int siz[N];
int P[N];
int deg[N];
vector<Node> tree;
int skok[LG+1][N];
void DFS(int v, int par)
{
siz[v] = 1, pre[v] = ++cnt, P[v] = par, tree[cnt+base] = {v,A[v]};
for(auto x : G[v])
{
if(x == par) continue;
deg[x] = deg[v] + 1, DFS(x,v), siz[v] += siz[x];
}
}
Node query(int l, int p)
{
l = l + base - 1, p = p + base + 1;
Node res = {-1,-1};
while(l/2 != p/2)
{
if(l % 2 == 0) res = max(res,tree[l+1]);
if(p % 2 == 1) res = max(res,tree[p-1]);
l /= 2, p /= 2;
}
return res;
}
void update(int v, Node val)
{
v += base, tree[v] = val, v /= 2;
while(v > 0) tree[v] = max(tree[v*2],tree[v*2+1]), v /= 2;
}
int LCA(int x, int y)
{
if(deg[x] < deg[y]) swap(x,y);
for(int i = LG; i >= 0; --i)
{
int v = skok[i][x];
if(deg[v] >= deg[y]) x = v;
}
if(x == y) return x;
for(int i = LG; i >= 0; --i)
{
int vx = skok[i][x], vy = skok[i][y];
if(vx != vy) x = vx, y = vy;
}
return skok[0][x];
}
int odl(int a, int b)
{
return deg[a] + deg[b] - 2*deg[LCA(a,b)];
}
ll DFS2(int v, int b)
{
vis[v] = 1;
ll val = 0;
update(pre[v],{-1,-1});
for(auto x : G[v])
{
if(vis[x]) continue;
if(deg[x] > deg[v])
{
Node akt = query(pre[x],pre[x]+siz[x]-1);
val = max(val,(ll)odl(v,akt.v)+DFS2(akt.v,x));
}
}
if(v != b)
{
Node akt = query(pre[b],pre[b]+siz[b]-1);
val = max(val,(ll)odl(v,akt.v)+DFS2(akt.v,b));
}
return val;
}
void solve()
{
cin >> n;
for(int i = 1; i <= n; ++i) cin >> A[i];
rep(i,n-1)
{
int a,b;
cin >> a >> b;
G[a].pb(b), G[b].pb(a);
}
base = 1;
while(base <= n+5) base *= 2;
rozmiar_drzewa = base * 2;
tree.assign(rozmiar_drzewa,{-1,-1});
deg[1] = 1, DFS(1,0);
for(int i = base-1; i >= 1; --i) tree[i] = max(tree[i*2],tree[i*2+1]);
for(int i = 1; i <= n; ++i) skok[0][i] = P[i];
for(int i = 1; i <= LG; ++i) for(int v = 1; v <= n; ++v) skok[i][v] = skok[i-1][skok[i-1][v]];
int wie = 1;
for(int i = 1; i <= n; ++i) if(A[i] == n) wie = i;
cout << DFS2(wie,1) << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
//cin >> T;
while(T--) solve();
return 0;
}
