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

int N;
int Q;
int parent[500100];
vector<int> children[500100];
int pre[500100];
int invpre[500100];
int post[500100];
long long int lst[500100];
int ft[500100];
const long long int inf = 1e18;
int cont = 1;

struct node{
	
	int s, m, e;
	pair<long long int,int> v;
	long long int lazy = 0;
	int v1 = 0;
	int lazy1 = 0;
	node *l, *r;
	
	
	node(int S, int E){
		s = S;
		e = E;
		m = (s + e)/2;
		
		if(s != e){
			l = new node(s,m);
			r = new node(m + 1, e);
			v = min(l -> v, r -> v);
		}
		else v = {lst[invpre[s]],invpre[s]};
	}
	
	void update(int S, int E, int k){
		if(S <= s && e <= E){
			v.first += k;
			lazy += k;
			return;
		}
		
		if(S <= m) l -> update(S,E,k);
		if(m < E) r -> update(S,E,k);
		
		v = min(l -> v, r -> v);
		v.first += lazy;
	}
	
	void remove(int i){
		if(s == e){
			v = {inf,-1};
			return;
		}
		if(i <= m) l -> remove(i);
		else r -> remove(i);
		
		v = min(l -> v, r -> v);
		v.first += lazy;
	}
	
	void update1(int S, int E){		
		if(S <= s && e <= E){		
			v1++;
			lazy1++;
			return;
		}
		
		if(S <= m) l -> update1(S,E);
		if(m < E) r -> update1(S,E);
		
		v1 = max(l -> v1, r -> v1) + lazy1; 
	}
	
}*root;

void dfs(int i){
	pre[i] = cont;
	cont++;
	
	for(int j : children[i]) dfs(j);
	
	post[i] = cont - 1;
}

int main(){
	scanf(" %d",&N);
	scanf(" %d",&Q);
	
	parent[1] = -1; 
	for(int i = 2; i <= N; i++){
		scanf(" %d",&parent[i]);
		children[parent[i]].push_back(i);
	}
	
	for(int i = 1; i <= N; i++){
		scanf(" %lld",&lst[i]);
	}
	
	dfs(1);
	
	for(int i = 1; i <= N; i++) invpre[pre[i]] = i;
	
	root = new node(1,N);
	
	for(int i = 0; i < Q; i++){
		int u,v;
		
		scanf(" %d",&u);
		scanf(" %d",&v);
		
		root -> update(pre[u],post[u],-v);
		while((root -> v).first <= 0){
			int it = (root -> v).second;
			root -> update1(pre[it],post[it]);
			root -> remove(pre[it]);
		}
		
		printf("%d\n",root -> v1);
	}
	
}