Validating Radio Buttons in two directions

I'm kind of a newbie so speak sllllooooowly. I've got a problem with validating radio buttons that seems to be harder than I think to solve. I've got ten items set up like this: Green: <input type="Radio" name="color1" value="1" /> <input type="Radio" name="color1" value="2" /> <input type="Radio" name="color1" value="3" /> and son on out to 10. Then I've got Red: <input type="Radio" name="color2" value="1" /> and so on out to ten again. So I've got ten colors each with 10 radio buttons so that they can be ranked from 1 to 10. The problem? Well, obviously, the user can only pick one value in the row for each color. That part is simple. BUT I also need to make sure that they only rank one color with the value "1" and, of course, only one color can have "2" and so on. How do I validate this so that they get a warning before they submit that user has picked more one color with the same ranking? An additional complication: They don't have to answer or rank all the colors. All they really need to do is rank one color to copmplete the question. I created an array with the answers and then used array_count_values to find out the frequency but that chokes on color rankings that are left blank. How do I assure that only one color is ranked at any one value? I hope my question makes sense. Any help will be appreciated. Thanks in advance. HiFi Tubes a retro kinda' guy who values quality over convenience