#include <iostream>
#include <vector>
#include <map>
#include <set>
using namespace std;

int main()
{
    int n;
    long long k;
    cin>>n>>k;
    vector<int> nums(n);
    multiset<int> maxk;
    map<int,int> lastseen;
    for(int & x:nums)cin>>x;
    int j=0;
    long long sum=0;
    int i=0;
    for(;i<k;i++)
        {
        lastseen[nums[i]]=i;
        maxk.insert(nums[i]);
        sum+=nums[i];
        }
    long long sv=*maxk.rbegin()+lastseen[*maxk.rbegin()]-j;

    long long ans=(double(sv+sv-k+1)/2)*k-sum;
    //cout<<ans;
    while(i<n)
        {

        maxk.erase(maxk.find(nums[j]));
        maxk.insert(nums[i]);
        sum-=nums[j];
        j++;
        lastseen[nums[i]]=i;
        sum+=nums[i];
        sv=*maxk.rbegin()+lastseen[*maxk.rbegin()]-j;
        ans=min(ans,((sv+sv-k+1)*k)/2-sum);
        //cout<<i<<" "<<j<<"\n";
        i++;
        }
    cout<<ans;

    return 0;
}