/* package whatever; // don't place package name! */
import java.util.regex.Pattern;
import java.util.regex.Matcher;
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
	{
		Pattern pat = Pattern.compile( "^(?!.*__)(?=[A-Za-z])[a-z A-Z0-9_]+(?<![ _])$" );
		String text = "c             a                      b                      d";
		for ( int i=0; i<100; i++ ) {
			long t1 = System.currentTimeMillis();
 
			test(text, pat);
 
			long t2 = System.currentTimeMillis();
	        System.out.println( t2 - t1 ) ;
		}
	}
 
	public static boolean test(String text, Pattern p) {
		boolean b = false;
		for ( int i=0; i<400000; i++ ) {
                 b = match(text, p);
        }
 
		return b;
	}
 
	public static boolean match(String text, Pattern p) {
		Matcher m = p.matcher( text );
 
		return m.matches();
	}
}

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