随便刷个水题，竟然被卡死在49分上。。。

#include<bits/stdc++.h>
using namespace std;
const double pi=3.1415926535897;
int n;
double x[101],y[101],r,s;
int main()
{
	scanf("%d %lf",&n,&r);
	double ans=(double)2*pi*r;
	for(int i=1;i<=n;i++)
	{
		scanf("%lf %lf",&x[i],&y[i]);
		s=(double)sqrt((x[i]-x[i-1])*(x[i]-x[i-1])+(y[i]-y[i-1])*(y[i]-y[i-1]));
		ans+=s;
	}
	ans+=(double)sqrt((x[n]-x[1])*(x[n]-x[1])+(y[n]-y[1])*(y[n]-y[1]));
	printf("%.2lf\n",ans);
	return 0;
}