Need help with some logic and how to do it in PHP

I have the following problem. I have 7 string values, if any number of them are the same, I need to ouput that value, if they are all different, I need to output a blank string "". How would I do this in php outside of writing a huge if/then statement? This is a variation of my "String compare of 7 text strings" question yesterday. All of the 7 string values are values in an array, ie $strings = array($string1, $string2, $string3, $string4, $string5, $string6, $string7); Thanks, Brent