import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }

string COLOR(string s = "") { return "\x1b[" ~ s ~ "m"; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readInt;
      const K = readInt;
      auto X = new real[N + 1];
      auto Y = new real[N + 1];
      foreach (u; 0 .. N) {
        X[u] = readLong;
        Y[u] = readLong;
      }
      X[N] = Y[N] = 0;
      
      auto D = new real[][](N + 1, N + 1);
      foreach (u; 0 .. N + 1) foreach (v; 0 .. N + 1) {
        D[u][v] = sqrt((X[u] - X[v])^^2 + (Y[u] - Y[v])^^2);
      }
      auto dp = new real[][][](1 << N, N + 1, K + 1);
      foreach (p; 0 .. 1 << N) foreach (u; 0 .. N + 1) dp[p][u][] = real.infinity;
      dp[0][N][K] = 0;
      foreach (p; 0 .. 1 << N) foreach (u; 0 .. N + 1) foreach (k; 0 .. K + 1) {
        if (k) {
          foreach (v; 0 .. N) chmin(dp[p | 1 << v][v][k - 1], dp[p][u][k] + D[u][v]);
        }
        chmin(dp[p][N][K], dp[p][u][k] + D[u][N]);
      }
      writefln("%.12f", dp[$ - 1][N][K]);
    }
  } catch (EOFException e) {
  }
}