#include<bits/stdc++.h>

using namespace std;

const int N = ;

const double pi = acos(-);

struct points {

    double x, y;

    bool friend operator < (points A, points B)

    {

        return A.x == B.x ? A.y < B.y : A.x < B.x;

    }

} point[N * ], p[N * ];

int n, m, cnt, top, kase;

double dp[ << N], d[ << N];

int st[N * ];

double cross(points x, points y, points z)

{

    return (x.x - z.x) * (y.y - z.y) - (x.y - z.y) * (y.x - z.x);

}

double dis(points x, points y)

{

    return sqrt((x.x - y.x) * (x.x - y.x) + (x.y - y.y) * (x.y - y.y));

}

double graham()

{

    double ret = ;

    top = ;

    for(int i = ; i <= cnt; ++i)

    {

        while(top >  && cross(p[i], p[st[top]], p[st[top - ]]) >= ) --top;

        st[++top] = i;

    }

    int lim = top;

    for(int i = cnt - ; i; --i)

    {

        while(top > lim && cross(p[i], p[st[top]], p[st[top - ]]) >= ) --top;

        st[++top] = i;

    }

    for(int i = ; i < top; ++i) ret += dis(p[st[i]], p[st[i + ]]);

    return ret;

}

int main()

{

    while(scanf("%d%d", &n, &m))

    {

        if(!n && !m) break;

        for(int i = ; i < n; ++i) scanf("%lf%lf", &point[i].x, &point[i].y);

        sort(point, point + n);

        for(int i = ; i < ( << n); ++i)

        {

            cnt = ;

            for(int j = ; j < n; ++j) if(i & ( << j))

                p[++cnt] = point[j];

            dp[i] = graham() +  * m * pi;

        }

        for(int i = ; i < ( << n); ++i)

            for(int S = i; S; S = (S - ) & i)

                dp[i] = min(dp[i], dp[S] + dp[i ^ S]);

        printf("Case %d: length = %.2f\n", ++kase, dp[( << n) - ]);

    }

    return ;

}