codeforces Round #263(div2) D. Appleman and Tree 树形dp

//зїеп:1085422276
#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <queue>
#include <typeinfo>
#include <map>
#include <stack>
typedef long long ll;
#define inf 100000000
#define mod 1000000007
using namespace std;

inline ll read()
{
ll x=0,f=1;
char ch=getchar();
while(ch<'0'||ch>'9')
{
if(ch=='-')f=-1;
ch=getchar();
}
while(ch>='0'&&ch<='9')
{
x=x*10+ch-'0';
ch=getchar();
}
return x*f;
}
//***************************************

struct ss
{

int to,next;
}e[200005*5];
ll dp[200005][2];
int head[200005],t,vis[200005],cl[200005];
void init(){
memset(head,0,sizeof(head));
t=1;
}
void add(int u,int v)
{
e[t].next=head[u];
e[t].to=v;
head[u]=t++;
}
void dfs(int x,int pre)
{
//vis[x]=1;
dp[x][cl[x]]=1;
for(int i=head[x];i;i=e[i].next)
{
if(e[i].to==pre)continue;
dfs(e[i].to,x);
if(cl[x]==1){
dp[x][1]=(dp[x][1]*dp[e[i].to][0]%mod+dp[x][1]*dp[e[i].to][1])%mod;
}
else {

dp[x][1]=(dp[x][1]*dp[e[i].to][0]%mod+dp[x][0]*dp[e[i].to][1]%mod+dp[x][1]*dp[e[i].to][1])%mod;
dp[x][0]=(dp[x][0]*dp[e[i].to][1]%mod+dp[x][0]*dp[e[i].to][0])%mod;
}

}
}

int main()
{
init();
int n;
scanf("%d",&n);
int x;
for(int i=0;i<n-1;i++){
scanf("%d",&x);
add(i+1,x);
add(x,i+1);
}
for(int i=0;i<n;i++)
scanf("%d",&cl[i]);
dfs(0,-1);
cout<<dp[0][1]<<endl;
return 0;
}