#include <bits/stdc++.h>
using namespace std;
const int INF = 1001001001;
const long long LINF = 1e18;
const double pi = 3.1415926535897932;
const string endstr = "\n";
template <typename T>
T gcd(T a, T b) {
  return (a == 0) ? b : gcd(b % a, a);
}
template <typename T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
bool p_comp_fs(const pair<long long, long long> p1,
               const pair<long long, long long> p2) {
  return p1.first < p2.first;
};
bool p_comp_fg(const pair<long long, long long> p1,
               const pair<long long, long long> p2) {
  return p1.first > p2.first;
};
bool p_comp_ss(const pair<long long, long long> p1,
               const pair<long long, long long> p2) {
  return p1.second < p2.second;
};
bool p_comp_sg(const pair<long long, long long> p1,
               const pair<long long, long long> p2) {
  return p1.second > p2.second;
};
template <typename T>
vector<T> uniquen(vector<T> vec) {
  sort((vec).begin(), (vec).end());
  vec.erase(unique(vec.begin(), vec.end()), vec.end());
  return vec;
}
inline long long popcnt(long long x) {
  return __builtin_popcountll((unsigned long long)x);
};
template <class T>
bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename Monoid>
struct SegmentTree {
  using F = function<Monoid(Monoid, Monoid)>;
  long long sz;
  vector<Monoid> seg;
  const F f;
  const Monoid M1;
  SegmentTree(long long n, const F f, const Monoid &M1) : f(f), M1(M1) {
    sz = 1;
    while (sz < n) sz <<= 1;
    seg.assign(2 * sz, M1);
  }
  void set(long long k, const Monoid &x) { seg[k + sz] = x; }
  void build() {
    for (long long k = sz - 1; k > 0; k--) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }
  void update(long long k, const Monoid &x) {
    k += sz;
    seg[k] = x;
    while (k >>= 1) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }
  Monoid query(long long a, long long b) {
    Monoid L = M1, R = M1;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1) L = f(L, seg[a++]);
      if (b & 1) R = f(seg[--b], R);
    }
    return f(L, R);
  }
  Monoid operator[](const long long &k) const { return seg[k + sz]; }
};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  long long N, C;
  cin >> N >> C;
  vector<long long> A(N);
  long long suma = 0;
  auto seg = SegmentTree<long long>(
      N, [](long long a, long long b) { return min(a, b); }, LINF);
  for (long long i = 0; i < N; i++) {
    cin >> A[i];
    suma += A[i];
    seg.update(i, A[i]);
  }
  vector<long long> dp(N + 1, 0);
  for (long long i = 0; i < N; i++) {
    if (i + C <= N) {
      long long q = seg.query(i, i + C);
      chmax(dp[i + C], dp[i] + q);
    }
    chmax(dp[i + 1], dp[i]);
  }
  long long mx = dp[N];
  cout << suma - mx << endstr;
  return 0;
}
