#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  bool zero = false;
  int *arr = new int[n];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  int neg = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] < 0) neg++;
    if (arr[i] == 0) {
      zero = true;
    }
  }
  for (int i = 0; k > 0 && i < neg;) {
    arr[i] = arr[i] * -1;
    k--;
    i++;
  }
  long long int ans = 0;
  for (int i = 0; i < n; i++) {
    ans += arr[i];
  }
  int min = INT_MAX;
  for (int i = 0; i < n; i++) {
    if (arr[i] < min) {
      min = arr[i];
    }
  }
  if (k % 2 == 0) {
    cout << ans;
  } else {
    cout << ans - 2 * min;
  }
  return 0;
}
