#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < int(n); i++)
#define rep1(i,n) for (int i = 1; i <= int(n); i++)
#define repR(i,n) for (int i = int(n)-1; i >= 0; i--)
#define rep1R(i,n) for (int i = int(n); i >= 1; i--)
#define loop(i,a,B) for (int i = a; i B; i++)
#define loopR(i,a,B) for (int i = a; i B; i--)
#define all(x) (x).begin(), (x).end()
#define mp make_pair
#define fst first
#define snd second
#define cauto const auto
#ifdef LOCAL
#define dump(...) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] ", my_dmp(#__VA_ARGS__, __VA_ARGS__)
void my_dmp(const char*) { cerr << endl; }
template <class T, class... U>
void my_dmp(const char *s, T const& x, U const& ...y) { const char *o = "({[", *e = "]})"; for (int i = 0; *s != '\0'; cerr << *s++) { if (count(o,o+3,*s)) i++; if (count(e,e+3,*s)) i--; if (!i && *s == ',') break; } cerr << " = " << x; if (*s == ',') cerr << ", ", s++; my_dmp(s, y...); }
#else
#define dump(...)
#endif
using ll = long long;
#define int ll
template <class T> using pque_max = priority_queue<T>;
template <class T> using pque_min = priority_queue<T, vector<T>, greater<T> >;
#define CONAINER_OUTPUT os << "{"; for (auto const& x : v) os << " " << x; return os << " }";
template <class T> ostream& operator<<(ostream& os, vector<T> const& v) { CONAINER_OUTPUT }
template <class T> ostream& operator<<(ostream& os, deque<T> const& v) { CONAINER_OUTPUT }
template <class T> ostream& operator<<(ostream& os, set<T> const& v) { CONAINER_OUTPUT }
template <class T> ostream& operator<<(ostream& os, multiset<T> const& v) { CONAINER_OUTPUT }
template <class T, class U> ostream& operator<<(ostream& os, map<T,U> const& v) { CONAINER_OUTPUT }
#undef CONAINER_OUTPUT
template <class T> istream& operator>>(istream& is, vector<T>& v) { for (auto& x : v) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T,S> const& p) { return os << "(" << p.first << ", " << p.second << ")"; }
template <class T, class S> istream& operator>>(istream& is, pair<T,S>& p) { return is >> p.first >> p.second; }
struct my_Init { my_Init() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); } } my_init;

template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T> bool chmin(T& x, T const& y) { if (x > y) { x = y; return true; } return false; }
template <class T> bool chmax(T& x, T const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits<It>::value_type{}); }
////////////////////////////////
vector<vector<int> > g;
vector<int> x;

int run(int x, vector<int> const& v) {
    const int N = 5000+10;
    static vector<int> s(N),t(N);
    rep (i,N) s[i] = t[i] = 0;

    s[0] = t[0] = 1;
    for (int y : v) {
        rep (i,N) if (s[i] && 0 <= i+y && i+y < N) t[i+y] = 1;
        rep (i,N) s[i] = t[i];
    }
    loopR (i,x,>=0) if (s[i]) return x-i;
    assert(0); return -1;
}

int dfs(int s) {
    if (g[s].empty()) return 0;
    vector<int> v; v.reserve(g[s].size());
    int sum = 0, sum2 = 0;
    for (int t : g[s]) {
        int a = dfs(t), b = x[t];
        if (a < 0) return -1;
        if (a > b) swap(a,b);
        sum += a;
        sum2 += a+b;
        v.push_back(b-a);
    }
    if (sum > x[s]) return -1;
    int val = run(x[s]-sum,v);
    int res = sum2+val-x[s];
    assert(res >= 0);
    dump(s,res);
    return res;
}

int32_t main() {
    int n; cin >> n;
    g.resize(n);
    x.resize(n);
    rep1 (i,n-1) {
        int p; cin >> p; p--;
        g[p].push_back(i);
    }
    cin >> x;
    cout << (dfs(0) >= 0 ? "POSSIBLE" : "IMPOSSIBLE") << "\n";
}


Measured memory_bytes: 512