Count the Number of Special Characters II
You are given a string word. A letter c is called special if it appears both in lowercase and uppercase in word, and every lowercase occurrence of c appears before the first uppercase occurrence of c.
Return the number of special letters in word.
Example 1
Input
word = "aaAbcBC"Output
3The special characters are
'a', 'b', and 'c'.Example 2
Input
word = "abc"Output
0There are no special characters in
word.Constraints
- 1 <= word.length <= 2 * 10^5
- word consists of only lowercase and uppercase English letters.