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


int main(){
    int n,req;
    cin >> n >> req;
    vector <int> graph[n];
    int val[n];
    int a;
    for(int i=0;i<n;i++){
        cin >> val[i];
    }
    int b;
    for(int i=1;i<n;i++){
        cin >> b;
        graph[b-1].push_back(i);
    }
    int count=0;
    for(int i=0;i<n;i++){
        int value = val[i];
        int sum = req - value;
        vector <int> children;
        for(int j=0;j<graph[i].size();j++){
            children.push_back(graph[i][j]);
        }
        for(int j=0;j<children.size();j++){
            for(int k=0;k<graph[children[j]].size();k++)
                children.push_back(graph[children[j]][k]);
        }

        for(int j=0;j<children.size();j++){
            for(int k=j+1;k<children.size();k++)
                if(val[children[j]]+val[children[k]]>=sum){
                    count++;
                }
        }
    }

    cout << count << endl;
}