use proconio::input;

const ORIGIN: (f64, f64) = (0.0, 0.0);

fn main() {
    input! {
        (n, k): (usize, usize),
        xy: [(f64, f64); n],
    }

    // dp[S][i][j]
    // S: 既に完了した注文の集合
    // i: 現在位置
    // j: 手持ちのピザの個数
    let mut dp: Vec<Vec<Vec<Option<f64>>>> = vec![vec![vec![None; k]; n + 1]; 1 << n];
    for pos in 0..n {
        dp[1 << pos][pos][k - 1] = Some(calc_distance(ORIGIN, xy[pos]));
    }

    for bits in 0_usize..1 << n {
        for from in 0..n {
            for num_pizzas in 0..k {
                let Some(cost) = dp[bits][from][num_pizzas] else {
                    continue;
                };

                for to in 0..n {
                    if bits >> to & 1 == 1 {
                        continue;
                    }

                    if num_pizzas >= 1 {
                        chmin_for_option(
                            &mut dp[bits | 1 << to][to][num_pizzas - 1],
                            cost + calc_distance(xy[from], xy[to]),
                        );
                    }

                    chmin_for_option(
                        &mut dp[bits | 1 << to][to][k - 1],
                        cost + calc_distance_via_origin(xy[from], xy[to]),
                    );
                }
            }
        }
    }

    let mut min_cost = None;
    for pos in 0..n {
        for num_pizzas in 0..k {
            if let Some(cost) = dp[(1 << n) - 1][pos][num_pizzas] {
                chmin_for_option(&mut min_cost, cost + calc_distance(xy[pos], ORIGIN));
            }
        }
    }
    println!("{}", min_cost.unwrap());
}

fn calc_distance(coord1: (f64, f64), coord2: (f64, f64)) -> f64 {
    (coord1.0 - coord2.0).hypot(coord1.1 - coord2.1)
}

fn calc_distance_via_origin(coord1: (f64, f64), coord2: (f64, f64)) -> f64 {
    calc_distance(coord1, ORIGIN) + calc_distance(ORIGIN, coord2)
}

/// If `value` is `None` or contains a value greater than `cand_value`, update it to `Some(cand_value)`.
///
/// Returns whether `value` has been updated or not as a bool value.
///
/// # Arguments
///
/// * `value` - Reference variable to be updated.
/// * `cand_value` - Candidate value for update.
pub fn chmin_for_option<T>(value: &mut Option<T>, cand_value: T) -> bool
where
    T: PartialOrd,
{
    if value.as_ref().is_some_and(|cost| cost <= &cand_value) {
        return false;
    }

    *value = Some(cand_value);

    true
}