/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.util.regex.*;
 
/* 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 s = "INITIAL TEXT\\KEYWORD1\\TEXT1\\KEYWORD2\\TEXT2\\KEYWORD3\\TEXT3";
    	Pattern pattern = Pattern.compile(("^.*?(?=\\\\(?:KEYWORD1|KEYWORD2|KEYWORD3)\\\\|$)"));
		Matcher matcher = pattern.matcher(s);
		if (matcher != null && matcher.find()) {
			System.out.println("found " + matcher.group(0) + "\n");
		}     	
	}
}

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