#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 2e5 + 10;
int n, a[maxn], used[maxn], pos[maxn];
vector < int > adj[maxn];
ll dp[maxn];
int rec(int val)
{
if (used[val])
return dp[val];
used[val] = 1;
int left = 0, right = n + 1;
for (int i = n; i > val; i --)
{
if (pos[i] > pos[val])
{
right = min(right, pos[i]);
}
else
{
left = max(left, pos[i]);
}
}
int mx = -1;
for (int i = pos[val] + 1; i < right; i ++)
{
if (a[i] > mx)
{
mx = a[i];
dp[val] = max(dp[val], (ll)(i - pos[val] + rec(a[i])));
}
}
mx = -1;
for (int i = pos[val] - 1; i > left; i --)
{
if (a[i] > mx)
{
mx = a[i];
dp[val] = max(dp[val], (ll)(pos[val] - i + rec(a[i])));
}
}
return dp[val];
}
int dfs(int v, int p, int mx, int dis, int val)
{
if (mx > val)
return 0;
int ans = 0;
if (a[v] == mx)
ans = max((ll)ans, dis + dp[v]);
for (int u : adj[v])
{
if (u == p)
continue;
ans = max(ans, dfs(u, v, max(mx, a[u]), dis + 1, val));
}
return ans;
}
int bef[maxn], aft[maxn];
pair < int, int > tree[4 * maxn];
void build_tree(int root, int left, int right)
{
if (left == right)
{
tree[root] = {a[left], left};
return;
}
int mid = (left + right) / 2;
build_tree(root * 2, left, mid);
build_tree(root * 2 + 1, mid + 1, right);
tree[root] = max(tree[root * 2], tree[root * 2 + 1]);
}
pair < int, int > query(int root, int left, int right, int qleft, int qright)
{
if (left > qright || right < qleft)
return {-1, -1};
if (left >= qleft && right <= qright)
return tree[root];
int mid = (left + right) / 2;
return max(query(root * 2, left, mid, qleft, qright),
query(root * 2 + 1, mid + 1, right, qleft, qright));
}
int best[maxn], par[maxn], depth[maxn];
int tin[maxn], tout[maxn], timer;
int occ[2 * maxn];
void trav(int v)
{
occ[++ timer] = v;
tin[v] = timer;
for (int u : adj[v])
{
if (u == par[v])
continue;
depth[u] = depth[v] + 1;
par[u] = v;
trav(u);
occ[++ timer] = v;
}
tout[v] = timer;
}
const int maxlog = 20;
int fp[maxlog][2 * maxn], lg[2 * maxn];
void build_sparse_table()
{
for (int i = 1; i <= timer; i ++)
{
lg[i] = lg[i / 2] + 1;
fp[0][i] = occ[i];
}
for (int j = 1; j < lg[timer]; j ++)
for (int i = 1; i <= timer - (1 << j) + 1; i ++)
{
fp[j][i] = fp[j - 1][i + (1 << (j - 1))];
if (depth[fp[j - 1][i]] < depth[fp[j][i]])
fp[j][i] = fp[j - 1][i];
}
}
int lca_query(int v, int u)
{
int l = tin[v], r = tin[u];
if (l > r)
swap(l, r);
int len = lg[r - l + 1] - 1, lca = fp[len][r - (1 << len) + 1];
if (depth[fp[len][l]] < depth[lca])
lca = fp[len][l];
return lca;
}
int distance(int v, int u)
{
return depth[v] + depth[u] - 2 * depth[lca_query(v, u)];
}
void solve()
{
cin >> n;
for (int i = 1; i <= n; i ++)
{
cin >> a[i];
pos[a[i]] = i;
}
bool chain = true;
for (int i = 1; i < n; i ++)
{
int v, u;
cin >> v >> u;
if (!(v == i && u == i + 1))
chain = false;
adj[v].push_back(u);
adj[u].push_back(v);
}
if (chain)
{
stack < int > st;
for (int i = 1; i <= n; i ++)
{
while(!st.empty() && a[st.top()] < a[i])
st.pop();
if (!st.empty())
bef[i] = st.top();
///cout << "stack " << i << " " << st.top() << endl;
st.push(i);
}
while(!st.empty())
st.pop();
for (int i = n; i > 0; i --)
{
while(!st.empty() && a[st.top()] < a[i])
st.pop();
if (!st.empty())
aft[i] = st.top();
else
aft[i] = n + 1;
st.push(i);
}
build_tree(1, 1, n);
for (int i = 1; i <= n; i ++)
{
int v = pos[i];
///cout << "now " << v << " " << bef[v] << " " <<aft[v] << endl;
pair < int, int > lf = query(1, 1, n, bef[v] + 1, v - 1);
pair < int, int > rf = query(1, 1, n, v + 1, aft[v] - 1);
///cout << v << " " << lf.second << " " << rf.second << endl;
if (lf.first != -1)
{
///cout << "here " << dp[lf.first] << " " << lf.first << endl;
dp[v] = max(dp[v], dp[lf.second] + (ll)(v - lf.second));
}
if (rf.first != -1)
dp[v] = max(dp[v], dp[rf.second] + (ll)(rf.second - v));
//cout << dp[v] << endl;
}
cout << dp[pos[n]] << endl;
}
else
{
trav(1);
build_sparse_table();
for (int i = 1; i <= n; i ++)
{
int v = pos[i];
//cout << "step" << endl;
//cout << v << endl;
for (int u : adj[v])
{
///cout << u << endl;
if (u == par[v])
continue;
///cout << "fine" << endl;
if (best[u] != 0)
{
///cout << "here " << best[u] << endl;
dp[v] = max(dp[v], dp[pos[best[u]]] + distance(v, pos[best[u]]));
}
}
int ver = par[v];
while(ver != 0)
{
if (a[ver] > i)
break;
//cout << "check " << v << " " << ver << " " << best[ver] << " " << pos[best[ver]] << " " << dp[best[ver]] << endl;
dp[v] = max(dp[v], dp[pos[best[ver]]] + distance(v, pos[best[ver]]));
ver = par[ver];
}
ver = v;
while(ver != 0)
{
if (a[ver] > i)
break;
best[ver] = i;
ver = par[ver];
}
///cout << "dp " << v << " " << dp[v] << endl;
}
cout << dp[pos[n]] << endl;
}
}
int main()
{
solve();
return 0;
}
/**
5
5 3 2 1 4
1 2
2 3
3 4
4 5
*/
