# 题目

## Description

This task will exclusively concentrate only on the arrays where all elements equal 1 and/or 2.

Array a is k-period if its length is divisible by k and there is such array b of length k, that a is represented by array b written exactly times consecutively. In other words, array a is k-periodic, if it has period of length k.

For example, any array is n-periodic, where n is the array length. Array [2, 1, 2, 1, 2, 1] is at the same time 2-periodic and 6-periodic and array [1, 2, 1, 1, 2, 1, 1, 2, 1] is at the same time 3-periodic and 9-periodic.

For the given array a, consisting only of numbers one and two, find the minimum number of elements to change to make the array k-periodic. If the array already is k-periodic, then the required value equals 0.

## Input

The first line of the input contains a pair of integers n, k (1 ≤ k ≤ n ≤ 100), where n is the length of the array and the value n is divisible by k. The second line contains the sequence of elements of the given array a1, a2, ..., an (1 ≤ ai ≤ 2), ai is the i-th element of the array.

## Output

Print the minimum number of array elements we need to change to make the array k-periodic. If the array already is k-periodic, then print 0.

## Sample Input

6 2
2 1 2 2 2 1

1

8 4
1 1 2 1 1 1 2 1

0

### Input

9 3
2 1 1 1 2 1 1 1 2

3

## Hint

In the first sample it is enough to change the fourth element from 2 to 1, then the array changes to [2, 1, 2, 1, 2, 1].

In the second sample, the given array already is 4-periodic.

In the third sample it is enough to replace each occurrence of number two by number one. In this case the array will look as [1, 1, 1, 1, 1, 1, 1, 1, 1] — this array is simultaneously 1-, 3- and 9-periodic.

# 题解

`k` 为循环长度

# 代码

```/*
By:OhYee
Github:OhYee
Blog:http://www.oyohyee.com/
Email:oyohyee@oyohyee.com

かしこいかわいい？
エリーチカ！

*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <functional>
#include <bitset>
#include <iomanip>
using namespace std;

const int maxn = 105;
int num[maxn];

bool Do() {
int n,k;
if(!(cin >> n >> k))
return false;

int p = n / k;

memset(num,0,sizeof(num));

for(int i = 1;i <= n;i++) {
int t;
cin >> t;
if(t == 1)
num[i%k]++;
}

int ans = 0;
for(int i = 0;i < k;i++) {
ans += min(p- num[i],num[i]);
}

cout << ans << endl;

return true;
}

int main() {
cin.tie(0);
cin.sync_with_stdio(false);

while(Do());
return 0;
}
```