Counting Codes with Repetition Rules

How many possible codes are there which consists of exactly two characters taken from the letters $A$, $B$, $C$, $D$, $E$, and $F$, and the numbers $1$, $2$, $3$, $4$, and $5$, if letters may be repeated and numbers cannot be repeated? Examples of valid codes: $A5$, $5C$, $AC$, $DD$, and $43$.