Problem Description

Given a string \( S \) of odd length \( N \). Each character in \( S \) is an uppercase letter.

An IOI string is a string that satisfies all of the following conditions:

• Its length is odd.
• Each character is either I or O, and they alternate.
• The first character is I.

For example, I, IOI, IOIOIOI are IOI strings, but JOI, IIOOII, OIOIO are not IOI strings.

You can perform the following operation any number of times (including zero):

• Choose one character in the string \( S \) and change it to any uppercase letter.

Find the minimum number of operations needed to convert the string \( S \) into an IOI string.

Input Format

The input is given from the standard input in the following format:

\( N \) \( S \)

Output Format

Output the minimum number of operations needed to convert the string \( S \) into an IOI string.

Sample Input and Output

Sample Input #1

5
JJOOI

Sample Output #1

3

Sample Input #2

7
IOIOIOI

Sample Output #2

0

Sample Input #3

7
BEAVERS

Sample Output #3

7

Sample Input #4

5
OIOIO

Sample Output #4

5

Notes/Hints

Constraints

• \( 1 \leq N \leq 99 \).
• \( N \) is odd.
• \( S \) is a string of length \( N \).
• Each character in \( S \) is an uppercase letter.

Sample Explanation 1

For example, you can make \( S \) an IOI string with 3 operations as follows:
1. Change the first character of \( S \) to I.
2. Change the second character of \( S \) to O.
3. Change the third character of \( S \) to I.
It is impossible to make \( S \) an IOI string with fewer than 3 operations, so output 3.

Sample Explanation 2

Sometimes no operations are needed.

见题面 Input 部分

见题面 Output 部分