include <iostream>

include <vector>

include <algorithm>

using namespace std;

int main() { int N, K; cin >> N >> K;

vector<int> x(N);
for (int i = 0; i < N; i++) {
    cin >> x[i];
}

int min_time = INT_MAX;
for (int i = 0; i <= N - K; i++) {
    int left_pos = x[i];
    int right_pos = x[i + K - 1];
    int time = min(abs(left_pos), abs(right_pos)) + abs(right_pos - left_pos);
    min_time = min(min_time, time);
}

cout << min_time << endl;

return 0;

}