Formula to find highest payscale & earliest date in highest payscale group

Hi,

Which formula do I have to use to find the highest payscale group of a person and the earliest entry date of his current payscale group
Here's my data. Wanted values marked with X, I want to add an indicator in column D, to make filtering possible. As a result I need the earliest payscale entry date

Pers.no. Pay scale Start date
00100003 89 01/09/2000
00100003 90 01/01/2001 X
00100003 90 01/02/2002
00100003 90 01/10/2003
00100004 90 01/09/2001
00100004 90 01/10/2001
00100004 91 01/01/2002 X
00100004 91 01/01/2003
00100005 91 01/07/2005
00100005 91 01/01/2006
00100005 92 01/07/2006 X
00100005 92 01/01/2007
00100005 92 01/01/2008
00100008 88 01/01/2003 X
00100008 88 01/01/2008
00100008 88 01/07/2008
00100009 88 01/06/2008 X
00100010 88 01/07/2000
00100010 88 01/09/2000
00100010 88 01/01/2001
00100010 89 01/07/2007
00100010 90 01/01/2008 X
00100010 90 01/07/2008

Thanks in advance