C++ :

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#define pi 3.1415926539
using namespace std;
float juli(int,int);
float a[110][4];
int main()
{
	//freopen("input.txt","r",stdin);
	//freopen("output.txt","w",stdout);

	int n;
	float s=0.0;
	float r;
	scanf("%d%f",&n,&r);
	for(int i=1;i<=n;i++)
		scanf("%f%f",&a[i][1],&a[i][2]);
    int z=1;
	while(1)
	{
         if(z==n)
	    {
            s+=juli(n,1);
            break;
		}
	    s+=juli(z,z+1);
	    z++;

    }
	s+=2*pi*r;
	printf("%.2f",s);
	//system("pause");
}
float juli(int c,int d)
{
	float s;
    s=sqrt(pow(a[c][1]-a[d][1],2)+pow(a[c][2]-a[d][2],2));
	return s;
}