Difference between B and E is 2 Difference between E and G is 1 Difference between G and J is 2 Difference between J and L is 1 SO, it continous to be the difference of 2, 1, 2, 1, 2, 1, 2,1 Difference between L and O is 2 Difference between O and Q is is 1 Differnce between Q and T is 2 The ext letters are V and Y