private static void testManual( final int cnt )
    {
        final List<String> lst = new ArrayList<>( 100 );
        long start = System.currentTimeMillis();
        for ( int i = 0; i < cnt; ++i )
        {
            final String str = "Very long test string, which tells you about something " +
                "very-very important, definitely deserving to be interned #" + i;
            lst.add( manualIntern( str ) );
            if ( i % 10000 == 0 )
            {
                System.out.println( i + "; manual time = " + ( System.currentTimeMillis() - start ) / 1000.0 + " sec" );
                start = System.currentTimeMillis();
            }
        }
        System.out.println( "Total length = " + lst.size() );
    }