Модуль: Information encoding: text, graphics, sound. Problem solving

Задача

To encode the letters A, B, C, D, E, F, G, Z, I, a non-uniform ternary code is used that satisfies the Fano condition. For the letter A, the code word 0 is used; for the letter B, code word 10 is used; for the letter B, code word 11 is used; for the letter G, the code word 21 is used; for the letter D, the code word is 22. What is the minimum total length of the code words for the letters E, F, Z, I?