Question 13
A computer program generated all five-letter code words that can be formed by using letters A, B, C, D, E, F, G, X, Y, Z (repetition is allowed). When all these words are sorted according to the alphabetical order, the following list is obtained: AAAAA, AAAAB, ..., AAAAZ, AAABA, AAABB, ..., ZZZZY, ZZZZZ. Find the number of code words between CZYGB and XEFDA, not including these two code words.