Compare PDF documents and markup changes

We have PDF documents in English languages (25 pages all together) slightly changed from their previous version. Some words may have been changed or whole sections may have been added or lines/words/sections may have been deleted. We will send you two sets of PDF files (2008 versions and 2009 versions). What's required: - Compare visually the two sets, page by page and line-by line, word by word - Mark-up the 2009 version with red circles around words or lines or sections that have been changed so we can focus in what areas changes have taken place. - If many changes are identified on a line of text, you can just circle the whole line - Sections/lines fully removed in the 2009 versions should be marked in the relevant 2009 spot as 'line removed' or 'section removed', so it draws our attention. - Send us back the 2009 marked-up pdf documents The objective is that we can quickly identify the changes