#include<stdio.h>
#include<math.h>
#define PI acos(-1)
int main()
{
    int N,i;
    double r;
    scanf("%d%lf",&N,&r);
    double xx,yy,cx,cy,fx,fy,sum=0,tsum=0,y,x,z;
    y=2*r;
    x=PI*r/2.0;
    z=N*(y-x);
    scanf("%lf%lf",&xx,&yy);
    fx=xx;
    fy=yy;
    for(i=2;i<=N;i++)
    {
        scanf("%lf%lf",&cx,&cy);
        sum=y+sum+sqrt((xx-cx)*(xx-cx)+(yy-cy)*(yy-cy));
        xx=cx;
        yy=cy;
        if(i==N)
        {
            sum=y+sum+sqrt((xx-fx)*(xx-fx)+(yy-fy)*(yy-fy));
            break;
        }
    }
    tsum=sum-z;
    printf("%.2lf\n",tsum);
    return 0;
}

what is the test 2..?