import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;

enum inf = 10L^^12;

void main() {
    int n, k;
    scan(n, k);
    auto x = readln.split.to!(int[]);

    long ans = inf;

    foreach (i ; 0 .. n - k + 1) {
        long l = x[i].to!long;
        long r = x[i + k - 1].to!long;
        long tmp;

        if (r < 0) {
            tmp = abs(l);
        }
        else if (l < 0) {
            tmp = min(2*abs(l) + r, abs(l) + 2*r);
        }
        else {
            tmp = r;
        }

        debug {
            writefln("%d, %d", l, r);
        }

        ans = min(ans, tmp);
    }

    writeln(ans);
}






















void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}
