#ifdef t9unkubj
#include"debug.cpp"
//#include"template_no_debug.h"
#else 
#define dbg(...) 199958
#endif

#undef _GLIBCXX_DEBUG
#pragma GCC optimize("O3")
using namespace std;
#include<bits/stdc++.h>
using ll=long long;
using ull=unsigned long long;
template<class T>using vc=vector<T>;
template<class T>using vvc=vc<vc<T>>;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define REP(i,j,n) for(ll i=(j);i<(ll)(n);i++)
#define DREP(i,n,m) for(ll i=(n);i>=(m);i--)
#define drep(i,n) for(ll i=((n)-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
template<class T,class F>
bool chmin(T &x, F y){
    if(x>y){
        x=y;
        return true;
    }
    return false;
}
template<class T, class F>
bool chmax(T &x, F y){
    if(x<y){
        x=y;
        return true;
    }
    return false;
}
double pass_time=0;
void solve(){
    using ld=long double;
    int n,k;
    cin>>n>>k;
    vc<ll>x(n),y(n);
    rep(i,n)cin>>x[i]>>y[i];
    x.push_back(0);
    y.push_back(0);
    vc dp(1<<n,vc(k+1,vc<ld>(n+1,2e18)));
    dp[0][k][n]=0;
    using P=tuple<ld,int,int,int>;
    priority_queue<P,vector<P>,greater<P>>que;
    que.push({0,0,k,n});
    while(que.size()){
        auto [dis,cond,pizza,now]=que.top();que.pop();
        if(dis!=dp[cond][pizza][now])continue;
        rep(i,n){
            if(cond>>i&1)continue;
            if(pizza==0)continue;
            ld nxt=dis+sqrtl((x[i]-x[now])*(x[i]-x[now])+(y[i]-y[now])*(y[i]-y[now]));
            if(chmin(dp[cond+(1<<i)][pizza-1][i],nxt)){
                que.push({nxt,cond+(1<<i),pizza-1,i});
            }
        }
        if(chmin(dp[cond][k][n],dis+sqrtl(x[now]*x[now]+y[now]*y[now]))){
            que.push({dp[cond][k][n],cond,k,n});
        }
    }
    ld ans=2e18;
    rep(i,k+1){
        chmin(ans,dp.back()[i][n]);
    }
    cout<<fixed<<setprecision(20)<<ans<<endl;
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    pass_time=clock();
    int t=1;
    //cin>>t;
    while(t--)solve();
    pass_time=clock()-pass_time;
    dbg(pass_time/CLOCKS_PER_SEC);
}