import java.util.*;
import java.io.*;
// n k
// p_2 c_2
// ...
// p_n c_n
// x_1 y_1
// x_2 y_2
// ...
// x_k y_k

public class Main {
    static List<List<Integer>> graph; 
    static int n;
    static int[] min_dist_from_warp;
    static int[] depth; 
    static boolean[] isPortal;
    
    public static void bfs(int s) {
        depth = new int[n+1];
        Arrays.fill(depth, -1);
        
        Queue<Integer> q = new ArrayDeque<>();
        depth[s] = 0;
        q.add(s);
        
        while(!q.isEmpty()) {
            int now = q.poll();
            for (int next : graph.get(now)) {
                if (depth[next] == -1) {
                    depth[next] = depth[now] + 1 ;
                    q.add(next);
               }
           }
       }
    }
    
    public static int dfs(int now) {
        int min_dist = 200001;
        if(isPortal[now]) min_dist = 0;
        for (int next : graph.get(now)) {
            int from_child = dfs(next) + 1;
            min_dist = Math.min(from_child, min_dist);
        }
        return min_dist_from_warp[now] = min_dist;
    }
    
    
    
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        
        n = Integer.parseInt(st.nextToken());
        int k = Integer.parseInt(st.nextToken());
        
        graph = new ArrayList<>();
        isPortal = new boolean[n+1];
        for (int i=0; i<n+1; i++) {
            graph.add(new ArrayList<>());
        }
        int[] parents = new int[n+1];
        Arrays.fill(parents, -1);


        for (int i=2; i<n+1; i++) {
            st = new StringTokenizer(br.readLine());
        
            int p = Integer.parseInt(st.nextToken());
            int c = Integer.parseInt(st.nextToken());
            
            graph.get(p).add(i);
            
            if (c==1) {
                isPortal[i] = true;
            }
        }
        
        bfs(1);
        
        
        min_dist_from_warp = new int[n+1];
        dfs(1);

        StringBuilder sb = new StringBuilder();
        

        for (int i=0; i<k; i++) 
        {
            st = new StringTokenizer(br.readLine());
            int x = Integer.parseInt(st.nextToken());
            int y = Integer.parseInt(st.nextToken());
            
            int dist_portal = min_dist_from_warp[x];
            int dist_from_one = depth[y];
            
            if (dist_portal == 200001 || dist_from_one == -1) {
                sb.append(-1).append("\n");
            } else {
                 sb.append(dist_portal+dist_from_one).append("\n");
            }
            
            
            
        }
        System.out.println(sb);
        
        
        
        
        
        
        
        
    }
}