A.Roman and Browser

#include <bits/stdc++.h>
using namespace std;
int a[110];

int main()
{
    int n,k;
    scanf("%d%d",&n,&k);
    int sum_e = 0,sum_s = 0;
    for (int i = 1;i<=n;i++)
    {
        scanf("%d",&a[i]);
        if (a[i] == 1)
            sum_e++;
        else
            sum_s++;
    }
    int Max = 0;
    for (int i = 1;i<=k;i++)
    {
        int sub_e = 0,sub_s = 0;
        for (int j = i;j <= n;j += k)
        {
            if (a[j] == 1)
                sub_e++;
            else
                sub_s++;
        }
        Max = max(Max,abs((sum_e-sub_e)-(sum_s-sub_s)));
    }
    printf("%d\n",Max);


    return 0;
}