#include<fstream>
#include<set>
#include<queue>
using namespace std;
ifstream fin("deque.in");
ofstream fout("deque.out");
multiset<int>s;
queue<int>q;
int n,k,a;
long long r;
int main()
{
    fin>>n>>k;
    for(int i=1;i<=n;i++)
    {
        fin>>a;
        q.push(a);
        s.insert(a);
        if(i>k)
        {
            a=q.front();
            s.erase(s.find(a));
            q.pop();
        }
        if(i>=k)
            r+=*s.begin();
    }
    fout<<r;
}