Language: Java

public class Main {
    public static void main(String[] args) {
        FS fs = new FS();
        int n = fs.nextInt();
        int a[] = new int[n];
        for(int i =0;i<n;i++){
            a[i]=fs.nextInt();
        }
        int[] b = new int[n];
        for(int i=0;i<n;i++){
            b[a[i]]++;
        }
        for (int i=1;i<n;i++){
            b[i]+=b[i-1];
        }
        int[] c = new int[n];
        for (int i=n-1;i>=0;i--){
             c[b[a[i]]-1]=a[i];
             b[a[i]]--;
        }
        StringBuilder sb= new StringBuilder();
        for(int i=0;i<n;i++){
            sb.append(c[i]+" ");
        }
        sb.deleteCharAt(sb.length()-1);
        System.out.println(sb.toString());
    }
   static class FS {
    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() {
        return hasNextByte() ? buffer[ptr++] : -1;
    }

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

    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    public boolean hasNext() {
        skipUnprintable();
        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 int nextInt() {
        return (int) nextLong();
    }

    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();
        }
    }
}
}


Compiler output:
Main.java:29: error: cannot find symbol
    private final InputStream in = System.in;
                  ^
  symbol:   class InputStream
  location: class FS
Main.java:41: error: cannot find symbol
            } catch (IOException e) {
                     ^
  symbol:   class IOException
  location: class FS
Main.java:69: error: cannot find symbol
        if (!hasNext()) throw new NoSuchElementException();
                                  ^
  symbol:   class NoSuchElementException
  location: class FS
Main.java:84: error: cannot find symbol
        if (!hasNext()) throw new NoSuchElementException();
                                  ^
  symbol:   class NoSuchElementException
  location: class FS
4 errors