#include <bits/stdc++.h>
#ifdef DEMETRIO
#define deb(...) fprintf(stderr,__VA_ARGS__)
#define deb1(x) cerr << #x << " = " << x << endl
#else
#define deb(...) 0
#define deb1(x) 0
#endif
#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define fore(i,a,b) for(int i=a,ThxDem=b;i<ThxDem;++i)
#define SZ(x) ((int)x.size())
using namespace std;
typedef long long ll;

vector<int> g[1024];
int n;
bitset<5024> b;
int w[1024];
int s[1024];

int main(){
	scanf("%d",&n);
	fore(i,1,n){
		int k;
		scanf("%d",&k);k--;
		g[k].pb(i);
	}
	fore(i,0,n)scanf("%d",w+i);
	for(int x=n-1;x>=0;--x){
		b.reset();b[0]=1;
		for(int y:g[x])b=(b<<w[y])|(b<<(s[y]-w[y])),s[x]+=s[y];
		int k=-1;
		fore(i,0,w[x]+1)if(b[w[x]-i]){k=i;break;}
		if(k<0){puts("IMPOSSIBLE");return 0;}
		s[x]+=k;
	}
	puts("POSSIBLE");
	return 0;
}