Readonly ,Const Keyword with static Modifier

Question

can we use a static modifier with a Readonly and Const variable

 

my question is that i want to know what is diff. b/w

          public static const int ab = 13;
public static readonly int ab = 10;

 

and 

 

public  const int ab = 13;
public  readonly int ab = 10; 

 

because const and readonly variable are all ready static for a class