#include<bits/stdc++.h>
using namespace std;

const int N = 1005, INF = 0x3f3f3f3f;

vector<int>V[N];
int f[N][5005], g[N], h[N];

int n;

void Dfs (int x) {
	int a, b;
	f[x][0] = 0;
	for (auto v : V[x]) {
		Dfs(v);
		a = min(g[v], h[v]); b = max(g[v], h[v]);
		for (int j = h[x]; j >= a; --j) {
			if (b > j) f[x][j] = f[x][j - a] + b;
			else f[x][j] = min(f[x][j - a] + b, f[x][j - b] + a);
		}
		for (int j = 0; j < a; ++j) f[x][j] = INF;
	}
	g[x] = f[x][0];
	for (int i = 0; i <= h[x]; ++i) g[x] = min(g[x], f[x][i]);
	if (g[x] >= INF) puts("IMPOSSIBLE"), exit(0);
}

int main () {
	scanf("%d", &n);
	memset(f, 0x3f, sizeof f);
	for (int i = 2, j; i <= n; ++i) scanf("%d", &j), V[j].emplace_back(i);
	for (int i = 1; i <= n; ++i) scanf("%d", &h[i]);
	Dfs(1);
	return puts("POSSIBLE"), 0;
}