#include<bits/stdc++.h>
typedef long long ll ;
#define rep(i, a, b) for (int i = a; i <= b; ++i)
using namespace std;

template <typename tn> void read (tn & a) {
	tn x = 0, f = 1; char c = getchar();
	while (c < '0' || c > '9') { if (c == '-') f = 0; c = getchar(); }
	while (c >= '0' && c <= '9') { x = x * 10 + c - '0'; c = getchar(); }
	a = f == 1 ? x : -x;
}

const int MAXN = 1100;
const int INF = 1e9 + 7;
int n;
int p[MAXN], x[MAXN];
int f[MAXN][5100];

int main() {
	read(n);
	rep(i, 2, n) {
		read(p[i]);
	}
	rep(i, 1, n) read(x[i]);
	for (int i = n; i > 0; --i) {
		int t = INF;
		rep(j, 0, x[i]) {
			t = min(t, f[i][j]);
		}
		if (t >= INF) { printf("IMPOSSIBLE\n"); return 0; }
		int pa = p[i];
		for (int j = x[pa]; j >= 0; --j) {
			int fx = INF;
			if (j >= t) fx = min(fx, f[pa][j - t] + x[i]);
			if (j >= x[i]) fx = min(fx, f[pa][j - x[i]] + t);
			f[pa][j] = fx;
		}
	}
	printf("POSSIBLE\n");
	return 0;
}
