#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
using namespace std;
typedef long long ll;
int main()
{
  int N, K;
  cin >> N >> K;
  vector<ll> A(N);
  for (int i = 0; i < N; i++)
  {
    cin >> A[i];
  }
  vector<ll> c;
  ll sum = 0;
  for (int i = ssize(A) - 1; i >= 0; i--)
  {
    sum += A[i];
    if (K <= i && sum < 0)
    {
      sum = 0;
      c.clear();
    }
    else if (i != 0)
    {
      c.push_back(sum);
    }
  }
  ranges::sort(c, greater<ll>());
  cout << sum + accumulate(c.begin(), c.begin() + K-1, 0LL) << '\n';
  return 0;
}
/*
  File : ~/yukicoder/526/C.cpp
  Date : 2025/03/07
  Time : 21:45:15
*/