#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007;
long long mod2 = 998244353;
long long mod3 = 1000003;
long long mod4 = 998244853;
long long mod5 = 1000000009;
long long inf = 1LL << 60;
double pi = 3.141592653589793238462643383279L;
double eps = 1e-14;
int dh[4] = {1, -1, 0, 0};
int dw[4] = {0, 0, 1, -1};
int ddh[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int ddw[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
long long gcd(long long a, long long b) {
  if (a < b) swap(a, b);
  if (b == 0) return a;
  if (a % b == 0) return b;
  return gcd(b, a % b);
}
long long Pow(long long n, long long k) {
  long long ret = 1;
  long long now = n;
  while (k > 0) {
    if (k & 1) ret *= now;
    now *= now;
    k /= 2;
  }
  return ret;
}
long long beki(long long n, long long k, long long md) {
  long long ret = 1;
  long long now = n;
  while (k > 0) {
    if (k % 2 == 1) {
      ret *= now;
      ret %= md;
    }
    now *= now;
    now %= md;
    k /= 2;
  }
  return ret;
}
long long gyaku(long long n, long long md) { return beki(n, md - 2, md); }
long long popcount(long long n) {
  long long ret = 0;
  long long u = n;
  while (u > 0) {
    ret += u % 2;
    u /= 2;
  }
  return ret;
}
int dp[5000];
vector<int> v[5000];
int x[5000];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  int p[n];
  for (int i = 1; i < n; i++) {
    cin >> p[i];
    p[i]--;
    v[p[i]].push_back(i);
  }
  for (int i = 0; i < n; i++) cin >> x[i];
  queue<int> q;
  for (int i = 0; i < n; i++) {
    if (v[i].size() == 0) q.push(i);
  }
  int ans[n];
  int cnt[n];
  fill(cnt, cnt + n, 0);
  while (q.size() > 0) {
    int now = q.front();
    q.pop();
    bool ok[v[now].size() + 1][x[now] + 1];
    memset(ok, false, sizeof ok);
    ok[0][0] = true;
    for (int i = 0; i < v[now].size(); i++) {
      int ne = v[now][i];
      int mi = min(ans[ne], dp[ne] - ans[ne]);
      for (int j = 0; j < x[now] + 1; j++) {
        if (j + mi > x[now]) break;
        if (j + ans[ne] <= x[now]) ok[i + 1][j + ans[ne]] |= ok[i][j];
        if (j + dp[ne] - ans[ne] <= x[now])
          ok[i + 1][j + dp[ne] - ans[ne]] |= ok[i][j];
      }
    }
    ans[now] = -1;
    for (int i = x[now]; i >= 0; i--) {
      if (ok[v[now].size()][i]) {
        ans[now] = x[now] - i;
        break;
      }
    }
    if (ans[now] == -1) {
      cout << "IMPOSSIBLE" << endl;
      return 0;
    }
    dp[now] += ans[now];
    if (now == 0) break;
    dp[p[now]] += dp[now];
    cnt[p[now]]++;
    if (cnt[p[now]] == v[p[now]].size()) q.push(p[now]);
  }
  cout << "POSSIBLE" << endl;
}
