1 #include <iostream>
  2 #include <stdio.h>
  3 #include <string.h>
  4 #include <math.h>
  5 #include <stdlib.h>
  6 #include <algorithm>
  7 
  8 using namespace std;
  9 
 10 const int MAX=1005;
 11 const double eps=1e-6;
 12 
 13 typedef struct point
 14 {
 15     double x,y;
 16 }point;
 17 
 18 point c[MAX];
 19 int top;
 20 
 21 bool dy(double x,double y)
 22 {
 23     return x>y+eps;
 24 }
 25 bool xy(double x,double y)
 26 {
 27     return x<y-eps;
 28 }
 29 bool xyd(double x,double y)
 30 {
 31     return x<y+eps;
 32 }
 33 bool dyd(double x,double y)
 34 {
 35     return x>y-eps;
 36 }
 37 bool dd(double x,double y)
 38 {
 39     return fabs(x-y)<eps;
 40 }
 41 
 42 double crossProduct(point a,point b,point c)
 43 {
 44     return (c.x-a.x)*(b.y-a.y)-(c.y-a.y)*(b.x-a.x);
 45 }
 46 double dist(point a,point b)
 47 {
 48     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
 49 }
 50 
 51 bool cmp(point a,point b)
 52 {
 53     if(dd(a.y,b.y))
 54     {
 55         return xy(a.x,b.x);
 56     }
 57     return xy(a.y,b.y);
 58 }
 59 bool cmp1(point a,point b)
 60 {
 61     double len=crossProduct(c[0],a,b);
 62     if(dd(len,0.0))
 63     {
 64         return xy(dist(c[0],a),dist(c[0],b));
 65     }
 66     return xy(len,0.0);
 67 }
 68 
 69 point stk[MAX];
 70 
 71 double dis()
 72 {
 73     double sum=0.0;
 74     for(int i=0;i<top;i++)
 75     {
 76         sum+=dist(stk[i],stk[i+1]);
 77     }
 78     sum+=dist(stk[top],stk[0]);
 79     return sum;
 80 }
 81 
 82 double Graham(int n)
 83 {
 84     sort(c,c+n,cmp);
 85     sort(c+1,c+n,cmp1);
 86     top=0;
 87     stk[top++]=c[0];
 88     stk[top++]=c[1];
 89     stk[top++]=c[2];
 90     top--;
 91     for(int i=3;i<n;i++)
 92     {
 93         while(1)
 94         {
 95             point a,b;
 96             a=stk[top];
 97             b=stk[top-1];
 98             if(xyd(crossProduct(a,b,c[i]),0.0))
 99             {
100                 top--;
101             }
102             else
103                 break;
104         }
105         stk[++top]=c[i];
106     }
107     return dis();
108 }
109 
110 int main()
111 {
112     int i,j,k,t;
113     int n,m;
114     int cas=0;
115     scanf("%d",&t);
116     while(t--)
117     {
118         scanf("%d%d",&n,&m);
119         for(i=0;i<n;i++)
120         {
121             scanf("%lf%lf",&c[i].x,&c[i].y);
122         }
123         if(cas++)
124         {
125             printf("\n");
126         }
127         double re=4*acos(0.0)*m;
128         double sum=Graham(n);
129         printf("%.0lf\n",sum+re);
130     }
131 }