/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
/* 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
	{
        final String regex = "v=([^\\s&]*)";
        final String string = " https://m...content-available-to-author-only...e.com/watch?v=9tg3csrFVJw";
        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(string);
 
        if(matcher.find()) {
            System.out.println(matcher.group(1));
        }		
	}
}

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