#include <bits/stdc++.h>

const int MAXN = 1010;
int fa[MAXN], A[MAXN], f[MAXN], g[5010], h[5010], n;
void gmin(int & x, int y) { x > y ? x = y : 0; }
int main() {
	std::ios_base::sync_with_stdio(false), std::cin.tie(0);
	std::cin >> n;
	for (int i = 2; i <= n; ++i) std::cin >> fa[i];
	for (int i = 1; i <= n; ++i) std::cin >> A[i];
	for (int i = n; i; --i) {
		memset(g, 0x3f, A[i] + 1 << 2); const int I = *g; *g = 0;
		for (int j = i + 1; j <= n; ++j) if (fa[j] == i) {
			int n1 = I, n2 = I;
			for (int k = 0; k <= A[i]; ++k) {
				if (k >= f[j]) gmin(n1, g[k - f[j]]);
				if (k >= A[j]) gmin(n2, g[k - A[j]]);
				h[k] = std::min(std::min(n1 + A[j], n2 + f[j]), I);
			}
			memcpy(g, h, A[i] + 1 << 2);
		}
		f[i] = *std::min_element(g, g + A[i] + 1);
		if (f[i] == I) return std::cout << "IMPOSSIBLE" << std::endl, 0;
	}
	std::cout << "POSSIBLE" << std::endl;
	return 0;
}
