/* package whatever; // don't place package name! */
 
import java.util.*;
import java.util.regex.*;
import java.lang.*;
import java.io.*;
 
/* 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
	{
		String regex = "(?<!6)66(?!6)";
	    String text = "6678793346666786784966";
	    Pattern pattern = Pattern.compile(regex);
	    Matcher matcher = pattern.matcher(text);
	    int match=0;
	    while (matcher.find()) {
 
	        match++;
	    }
	    System.out.println("count is "+match);
	}
}

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