Interface,(multiple Inheritance)which one gets priority?

Question

namespace Assembly

{

   interface I1

   {

      void Function(); 

   } 

   interface I2

   {

      void Function(); 

   }

   class Implementation:I1,I2

   {

       public void Function()

      {

         Console.WriteLine("interface function is defined in class Implementation"); 

      } 

      static void Main()

      {

         Implementation object1 = new Implementation();

         object1.Function(); 

      } 

   } 

} 

 //NOW MY QUESTION IS...

Which interface Function is considered at the time of calling either I1 or I2?