Language: C++

// #define DEBUGGING
#include <bits/stdc++.h>
#define endl '\n'
#define ALL(V) (V).begin(), (V).end()
#define ALLR(V) (V).rbegin(), (V).rend()
template <typename T> using V = std::vector<T>;
template <typename T> using VV = V<V<T>>;
using ll = std::int64_t;
using ull = std::uint64_t;
using PLL = std::pair<ll, ll>;
using TLL = std::tuple<ll, ll, ll>;
template <typename T> const T& var_min(const T &t) { return t; }
template <typename T> const T& var_max(const T &t) { return t; }
template <typename T, typename... Tail> const T& var_min(const T &t, const Tail&... tail) { return std::min(t, var_min(tail...)); }
template <typename T, typename... Tail> const T& var_max(const T &t, const Tail&... tail) { return std::max(t, var_max(tail...)); }
template <typename T, typename... Tail> void chmin(T &t, const Tail&... tail) { t = var_min(t, tail...); }
template <typename T, typename... Tail> void chmax(T &t, const Tail&... tail) { t = var_max(t, tail...); }
template <typename T> const T& clamp(const T &t, const T &low, const T &high) { return std::max(low, std::min(high, t)); }
template <typename T> void chclamp(T &t, const T &low, const T &high) { return t = clamp(t, low, high); }
namespace init__ { struct InitIO { InitIO() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << std::fixed << std::setprecision(30); } } init_io; }
#define mv_rec make_v(init, tail...)
template <typename T> T make_v(T init) { return init; }
template <typename T, typename... Tail> auto make_v(T init, size_t s, Tail... tail) { return V<decltype(mv_rec)>(s, mv_rec); }
#undef mv_rec
#ifdef DEBUGGING
#include "../../debug/debug.cpp"
#else
#define DEBUG(...) 0
#define DEBUG_SEPARATOR_LINE 0
#endif
using namespace std;

bool ok = true;
const size_t SIZE = 5000;
V<ll> edges[SIZE];
X[SIZE];

PLL dfs(ll cur) {
    bitset<SIZE + 10> bs;
    bs.set(0, 1);
    ll sum = 0;
    for(ll nxt : edges[cur]) {
        ll a, b;
        tie(a, b) = dfs(nxt);
        if(!ok) return PLL();
        sum += a + b;
        bs = (bs << a) | (bs << b);
    }
    for(ll i = SIZE; 0<= i; i--) {
        if(!bs.test(i)) continue;
        if(X[cur] < i) continue;
        return PLL(X[cur], sum - i);
    }
    ok = false;
    return PLL();
}

int main() {
    ll N;
    cin >> N;
    X.resize(N);
    edges.resize(N);
    for(ll i = 1; i < N; i++) {
        ll c = i;
        ll p;
        cin >> p;
        edges[p - 1].push_back(c);
    }
    for(ll i = 0; i < N; i++) cin >> X[i];
    dfs(0);
    if(!ok) cout << "IM";
    cout << "POSSIBLE" << endl;
    return 0;
}


Compiler output:
a.cc:36:1: error: 'X' does not name a type
   36 | X[SIZE];
      | ^
a.cc: In function 'PLL dfs(ll)':
a.cc:51:12: error: 'X' was not declared in this scope
   51 |         if(X[cur] < i) continue;
      |            ^
a.cc:52:20: error: 'X' was not declared in this scope
   52 |         return PLL(X[cur], sum - i);
      |                    ^
a.cc: In function 'int main()':
a.cc:61:5: error: 'X' was not declared in this scope
   61 |     X.resize(N);
      |     ^
a.cc:62:11: error: request for member 'resize' in 'edges', which is of non-class type 'V<long int> [5000]' {aka 'std::vector<long int, std::allocator<long int> > [5000]'}
   62 |     edges.resize(N);
      |           ^~~~~~