#include <bits/stdc++.h>

using namespace std;
ifstream in("deque.in");
ofstream out("deque.out");
queue < int > q;
multiset < int > v;
int n,x,k;
long long sum=0;
int main()
{
    int i;
    in>>n>>k;
    for(i=1; i<=k; i++)
    {
        in>>x;
        q.push(x);
        v.insert(x);
    }
    sum+=*v.begin();
    v.erase(v.find(q.front()));
    q.pop();
    for(;i<=n; i++)
    {
        in>>x;
        q.push(x);
        v.insert(x);
        sum+=*v.begin();
        v.erase(v.find(q.front()));
        q.pop();
    }
    out<<sum;
    return 0;
}