There were twenty three letters in the Latin alphabet:
A B C D E F G H I K L M N
O P Q R S T U V X Y Z
In early times, letter 'C' in Latin alphabet represented a sound like hard 'g'. Rare remains of this pronunciation are found in the abbreviations 'C.' for 'Gaius' and 'Cn.' for 'Gnaeus'.
Later, 'C' was used for a 'k' sound: the 'g' sound was then represented by C with an added stroke, i.e., 'G'. K went out of use and was practically non-present in the Latin alphabet, except in a few words (e.g., Kalendae).
The small letters of the Latin alphabet did not come into general use until the Middle Ages. They were originally a cursive or a running-hand variation of the capitals. The small form of Latin 'V' was 'u'.
The letters 'Y' and 'Z' were added to Latin alphabet in Cicero's times. They were used only in words from the Greek, just as French uses 'W' in words taken from English.