import java.util.*;
import java.lang.*;
import java.io.*;
 
class Ideone
{
	private static void outputInterval(int a, int b) {
		System.out.println(String.format("[%d, %d]", a, b));
	}
 
	public static void main (String[] args) throws java.lang.Exception
	{
		int a[] = new int[]{1,2,3,4,5,7,8,9,10,15,16,21,23,25,26};
		int intervalStart = a[0];
		for (int i = 1; i < a.length; ++i) {
			if (a[i] > a[i-1]+1) {
				outputInterval(intervalStart, a[i-1]);
				intervalStart = a[i];
			}
		}
		outputInterval(intervalStart, a[a.length-1]);		
	}
}

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