#include <bits/stdc++.h>
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)

using namespace std;
using ll = long long;

ll op(ll a, ll b) { return min(a, b); }

ll e() { return 1e18; }

int main() {
    int n, k;
    cin >> n >> k;
    
    vector<int> a(n);
    rep(i, n) cin >> a[i];
    
    ll ans = 0;
    rep(i, n) ans += a[i];
    
    segtree<ll, op, e> t(n);
    rep(i, k) t.set(i, a[i]);
    for (int i = k; i < n; ++i) {
        ll now = t.prod(i-k, i)+a[i];
        t.set(i, now);
    }
    ans -= t.prod(n-k, n);
    
    cout << ans << '\n';
    
    return 0;
}