import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.concurrent.atomic.*;
import java.util.stream.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone{
	public static void main (String[] args) throws java.lang.Exception{
		AtomicInteger counter = new AtomicInteger(0);
		Integer[] array = {4, 2, 3, 4, 1, 1, 1, 2, 1};
 
		String res = Arrays.asList(array).stream()
			.collect(Collectors.groupingBy(it -> counter .getAndIncrement() / 3))
			.values().stream()
			.map(val-> val.stream().mapToInt(Integer::intValue).sum())
			.map(String::valueOf)
			.collect(Collectors.joining());
			System.out.println(res);
	}
}

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