Conditional Formatting based on cells in multiple sheets

Good Morning,

I have a question about how to highlight cells dependent on what has been entered into multiple sheets.

im using a spreadsheet for multiple people to track what tickets they have sold, we have 3 people mary, matt and joe. they enter the ticket numbers in their own sheets in column A. in sheet1 i want to have all the possible numbers of tickets, lets say 100 to 500, i then want to highlight each of these numbers depending on which number has been entered into any of the other sheets.

So if Mary sells tickets 100 and 101 and matt sells 102 and 103, i want the relevant numbers on sheet 1 to highlight green for Mary and Blue for Matt for example.

I did have this working previously in office 2010, but once i sent it to someone else the rules were removed and now i cant remember how i did it, or find the websites i used to create the formulas.

I would be grateful for the help or any suggestions of better ways to do what i need to do.

Thanks,

Matt