#include <iostream>
#include <fstream>
#include <set>

#if 1
#define pv(x) cout<<#x<<" = "<<x<<"; ";cout.flush()
#define pn cout<<endl
#else
#define pv(x)
#define pn
#endif

using namespace std;
ifstream in("deque.in");
ofstream out("deque.out");

using ll = long long;
using ull = unsigned long long;
using ui = unsigned int;
#define pb push_back
#define mp make_pair
const int NMax = 5e6 + 5;
const ll inf = 1e18 + 5;
const int mod = 100003;
using zint = int;

int N,K;
int v[NMax];

int main() {
    in>>N>>K;

    multiset< pair<int,int> > st;

    ll ans = 0;
    for (int i=1;i <= N;++i) {
        in>>v[i];
        st.insert( mp(v[i],i) );

        if (i >= K) {

            multiset<pair<int,int>>::iterator it = st.find(mp(v[i-K],i-K));
            if (it != st.end()) {
                st.erase(it);
            }

            auto p = *st.begin();
            //pv(p.first);pv(p.second);pn;
            ans += p.first;
        }
    }

    out<<ans<<'\n';

    in.close();out.close();
    return 0;
}