There is a strange printer with the following two special properties:

- The printer can only print a sequence of the same character each time.
- At each turn, the printer can print new characters starting from and ending at any place and will cover the original existing characters.

Given a string `s`, return the minimum number of turns the printer needed to print it.

Example 1:

    Input: s = "aaabbb"
    Output: 2
    Explanation: Print "aaa" first and then print "bbb".

Example 2:

    Input: s = "aba"
    Output: 2
    Explanation: Print "aaa" first and then print "b" from the second place of the string, which will cover the existing character 'a'.

Constraints:

- `1 <= s.length <= 100`
- `s` consists of lowercase English letters.