interface implementation with another interface

Question

//i am getting error the modifier public is not valid for this item

 

interface i
{
public void method1();

}

interface a:i
{
public void methoda();

}

class Program:a
{
static void Main(string[] args)
{
a obj1 = new Program();
obj1.method1();
Console.ReadLine();
}

void method1()
{
Console.WriteLine("methods1interface");
}
void methoda()
{
Console.WriteLine("methods1interface");
}

}
}