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  1. All Contests
  2. HourRank 8
  3. Beautiful Binary String

Beautiful Binary String

Alice has a binary string. She thinks a binary string is beautiful if and only if it doesn't contain the substring .

In one step, Alice can change a to a or vice versa. Count and print the minimum number of steps needed to make Alice see the string as beautiful.

Example

She can change any one element and have a beautiful string.

Function Description

Complete the beautifulBinaryString function in the editor below.

beautifulBinaryString has the following parameter(s):

  • string b: a string of binary digits

Returns

  • int: the minimum moves required

Input Format

The first line contains an integer , the length of binary string.
The second line contains a single binary string .

Constraints

  • .

Output Format

Print the minimum number of steps needed to make the string beautiful.

Sample Input 0

STDIN       Function
-----       --------
7           length of string n = 7
0101010     b = '0101010'

Sample Output 0

2

Explanation 0:

In this sample,

The figure below shows a way to get rid of each instance of :

Make the string beautiful by changing characters ( and ).

Sample Input 1

5
01100

Sample Output 1

0

Sample Case 1:

In this sample

Explanation 1

The substring does not occur in , so the string is already beautiful in moves.

Sample Input 2

10
0100101010

Sample Output 2

3

Explanation 2

In this sample

One solution is to change the values of to form a beautiful string.