Level 4

Break the code. K -> O O -> S E -> I ...

Hint 1

Each letter is shifted X positions in the alphabet. This encryption method is sometimes called Caesar chiffre.

Hint 2

Each letter has to be shifted 4 positions to the right in the alphabet. Position 1 (a) has to become position 5 (e).

Hint 3

plyr::mapvalues() (plus some preprocessing) is one way to do it. The builtin "letters" vector is useful.

Data

e dkla ukq zezjp pnwjohwpa ep xu dwjz. pdwpo sdwp ykilqpano wna bkn. zkejc ep xu dwjz eo ejabbeyeajp wjz pdwpo sdu pdeo patp eo ok hkjc. qoejc lhun::iwlrwhqao eo kja swu pk zk ep. wjuswu, pda okhqpekj eo lwjzwxawn.