Derive Good String

You have to solve $t$ cases. In each case, you are given a string $s$. You have to perform moves on the string $s$, to make it a good string. In one move, you can delete a character from string $s$. A good string, is a string in which the number of occurrences of every character is at most $1$. Find out the minimum number of moves required to make the given string $s$ a $good$ string,