PROGRAMMING:Garden, an old driver
Garden is not only the richest man in the world, but also an old driver. On Christmas Eve, he bought an island and a car for driving on it. Garden has a new set of winter tires that allow him to drive safely for no more than k days at any average air temperature. After using for K days (regardless of the temperature of these days), the tire wear is serious in winter and can not be driven any more. These K days do not need to form a continuous period of days.
Before the first winter, garden still uses summer tires. When the average air temperature is non negative, summer tires can be used to drive safely for any number of days. When the average air temperature is negative, you cannot continue to drive with summer tires. Garden can replace summer tires with winter tires at the beginning of any day and vice versa.
Garden found an interesting problem in driving many times, that is, whether the minimum number of tire replacement can be safely driven for n days. If it can, the minimum number of tire replacement will be output, otherwise - 1 will be output
###Input format:
The first line contains two positive integers n and K (1 ≤ n ≤ 20000, 0 ≤ K ≤ n) representing the total number of days N and the available days K of winter tires. It is allowed to drive winter tires at any temperature, but not more than k days in total.
The second line contains the sequence of N integers T1, T2,..., TN (- 20 ≤ Ti ≤ 20) to represent the average air temperature of day I.
###Output format:
The output garden needs to change the tire at least several times. If it is impossible to drive all the days, please output - 1.
###Input example:
Here is a set of inputs. For example:
```in
4 3
-5 20 -3 0
4 2
-5 20 -3 0
10 6
2 -5 1 3 0 0 -4 -3 1 0
```
###Output example:
The corresponding output is given here. For example:
```out
two
four
three
```
answer：If there is no answer, please comment
Before the first winter, garden still uses summer tires. When the average air temperature is non negative, summer tires can be used to drive safely for any number of days. When the average air temperature is negative, you cannot continue to drive with summer tires. Garden can replace summer tires with winter tires at the beginning of any day and vice versa.
Garden found an interesting problem in driving many times, that is, whether the minimum number of tire replacement can be safely driven for n days. If it can, the minimum number of tire replacement will be output, otherwise - 1 will be output
###Input format:
The first line contains two positive integers n and K (1 ≤ n ≤ 20000, 0 ≤ K ≤ n) representing the total number of days N and the available days K of winter tires. It is allowed to drive winter tires at any temperature, but not more than k days in total.
The second line contains the sequence of N integers T1, T2,..., TN (- 20 ≤ Ti ≤ 20) to represent the average air temperature of day I.
###Output format:
The output garden needs to change the tire at least several times. If it is impossible to drive all the days, please output - 1.
###Input example:
Here is a set of inputs. For example:
```in
4 3
-5 20 -3 0
4 2
-5 20 -3 0
10 6
2 -5 1 3 0 0 -4 -3 1 0
```
###Output example:
The corresponding output is given here. For example:
```out
two
four
three
```
answer：If there is no answer, please comment