#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  int a[n];
  for (int i = 0; i < n; ++i) cin >> a[i];
  sort(a, a + n);
  long long sum = 0;
  for (int i = 0; i < m; ++i) sum = max(sum, sum - a[i]);
  cout << sum << endl;
}
