Language: Java

import java.io.*;
import java.util.*;


public class AMain {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        int n = sc.nextInt();
        int[] a = new int[n];

        for(int i=0; i<n; i++){
            a[i] = sc.nextInt();
        }

        if(n % 3 != 0){
            for(int i=0; i<n; i++){
                if(a[i] != 0){
                    System.out.println("No");
                    return;
                }
            }
        }

        int m = 0;
        HashMap<Integer, Integer> map = new HashMap<>();
        ArrayList<Integer> key = new ArrayList<Integer>();
        for(int i=0; i<n; i++){
            if(map.get(a[i]) == null){
                map.put(a[i], 1);
                key.add(a[i]);
                m++;
            }else{
                map.put(a[i], map.get(a[i]) + 1);
            }
        }

        if(m > 3){
            System.out.println("No");
        }else if(m == 3){
            if(map.get(key.get(0)) == map.get(key.get(1)) &&
                map.get(key.get(1)) == map.get(key.get(2))){
                    System.out.println("Yes");
                }else{
                    System.out.println("No");
                }
        }else if(m == 2){
            if(map.get(key.get(0)) == 2 * map.get(key.get(1)) ||
            2 * map.get(key.get(0)) == map.get(key.get(1))){
                System.out.println("Yes");
            }else{
                System.out.println("No");
            }
        }else{
            if(map.get(key.get(0)) == 0){
                System.out.println("Yes");
            }else{
                System.out.println("No");
            }
        }


    }


    private static class FastScanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;

        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            } else {
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[ptr++];
            else
                return -1;
        }

        private static boolean isPrintableChar(int c) {
            return 33 <= c && c <= 126;
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[ptr]))
                ptr++;
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while (true) {
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
                throw new NumberFormatException();
            return (int) nl;
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }
}


Compiler output:
Main.java:5: error: class AMain is public, should be declared in a file named AMain.java
public class AMain {
       ^
1 error