#include <bits/stdc++.h>
using namespace std;
#define N 100010
int n, num, h[N], a[N], f[N][2][2];
struct node {
  int to, nxt;
} e[N << 1];
void ins(int x, int y) {
  e[++num].to = y;
  e[num].nxt = h[x];
  h[x] = num;
  e[++num].to = x;
  e[num].nxt = h[y];
  h[y] = num;
}
void dfs(int u, int father) {
  int sz = 0;
  int fa = 1, fb = 1;
  f[u][0][0] = a[u];
  f[u][0][1] = 0;
  f[u][1][0] = n + 1;
  f[u][1][1] = a[u];
  for (int i = h[u]; i; i = e[i].nxt) {
    int v = e[i].to;
    if (v == father) continue;
    ++sz;
    dfs(v, u);
    if (f[v][1][0] <= a[u] && f[v][0][0] <= a[u]) fa = 0;
    int t = n + 1;
    if (f[v][1][0] > a[u]) { t = min(f[v][1][1], t); }
    if (f[v][0][0] > a[u]) { t = min(f[v][0][1], t); }
    f[u][0][1] = max(f[u][0][1], t);
    t = 0;
    if (f[v][0][1] >= a[u] && f[v][1][1] >= a[u]) fb = 0;
    if (f[v][0][1] < a[u]) { t = max(f[v][0][0], t); }
    if (f[v][1][1] < a[u]) { t = max(f[v][1][0], t); }
    f[u][1][0] = min(f[u][1][0], t);
  }
  if (!sz) {
    f[u][0][0] = a[u];
    f[u][0][1] = 0;
    f[u][1][0] = n + 1;
    f[u][1][1] = a[u];
  } else {
    if (!fa) {
      f[u][0][0] = 0;
      f[u][0][1] = n + 1;
    }
    if (!fb) {
      f[u][1][0] = 0;
      f[u][1][1] = n + 1;
    }
  }
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) { scanf("%d", &a[i]); }
  for (int i = 1; i < n; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    ins(x, y);
  }
  memset(f, -1, sizeof(f));
  dfs(1, 0);
  if (f[1][0][0] == a[1] || f[1][1][1] == a[1]) puts("YES");
  else puts("NO");
  return 0;
}