# String

We are given a string S of length n that consists of zeros and ones. We would like to modify it in such a way that it will not contain the substring `"010"`

. (A substring is a subsequence of *consecutive* characters.) The only allowed operations is the *inversion of individual bits* (i.e. replacement of a `'1'`

with a `'0'`

or replacement of a `'0'`

with a `'1'`

). What is the minimal number of replacements that are needed to modify string S so that it will not contain the substring `"010"`

?

## Input

The first line contains integer n, i.e. the length of S. The second line contains the string S which consists of zeros and ones.

### Input limits

- 1 \leq n \leq 10^5

## Output

Output one number – the minimal number of required operations.

## Example

## Input7 0101010 | ## Output2 |

### Comment

In the above example we may obtain the string `"0001110"`

by two replacements. It does not contain the substring `"010"`

.

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