HackerEarth Coloring trees problem solution

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Collection;
import java.io.IOException;
import java.util.Queue;
import java.util.LinkedList;
import java.util.TreeSet;
import java.io.InputStream;

public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ColoringTheTree solver = new ColoringTheTree();
        int testCount = 1;
        for (int i = 1; i <= testCount; i++)
            solver.solve(i, in, out);
        out.close();
    }

    static class ColoringTheTree {
        PrintWriter out;
        InputReader in;

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            this.out = out;
            this.in = in;
            int n = ni();
            int k = ni();
            TreeSet<Integer>[] tree = new TreeSet[n];
            int i = 0;
            for (i = 0; i < n; i++)
                tree[i] = new TreeSet<>();
            int[] deg = new int[n];
            for (i = 0; i < n - 1; i++) {
                int u = ni() - 1;
                int v = ni() - 1;
                tree[u].add(v);
                tree[v].add(u);
                deg[u]++;
                deg[v]++;
            }
            boolean[] is_terminus = new boolean[n];
            for (i = 0; i < k; i++)
                is_terminus[ni() - 1] = true;
            Queue<Integer> qu = new LinkedList<>();
            for (i = 0; i < n; i++) {
                if (!is_terminus[i] && deg[i] == 1)
                    qu.add(i);
            }
            int not_visited = 0;
            while (qu.size() > 0) {
                int curr = qu.poll();
                for (int u : tree[curr]) {
                    tree[u].remove(curr);
                    deg[u]--;
                }
                for (int u : tree[curr]) {
                    if (deg[u] == 1 && !is_terminus[u])
                        qu.add(u);
                }
                not_visited++;
            }
            pn(n - not_visited);
        }

        int ni() {
            return in.nextInt();
        }

        void pn(long zx) {
            out.println(zx);
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new UnknownError();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new UnknownError();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public String next() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuffer res = new StringBuffer();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));

            return res.toString();
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == 'n' || c == 'r' || c == 't' || c == -1;
        }

    }
}