Selectivo 2 - P2

#include <iostream>
#include <cmath>

using namespace std;

int main(){
    int N;
    double r;

    cin >> N >> r;

    double x[100],y[100];

    for(int i = 0;i < N;++i)
        cin >> x[i] >> y[i];

    double ans = 2 * acos(-1.0) * r + sqrt((double)(x[N - 1] - x[0]) * (x[N - 1] - x[0]) + (double)(y[N - 1] - y[0]) * (y[N - 1] - y[0]));

    for(int i = 0;i + 1 < N;++i)
        ans += sqrt((double)(x[i + 1] - x[i]) * (x[i + 1] - x[i]) + (double)(y[i + 1] - y[i]) * (y[i + 1] - y[i]));

    printf("%.2f\n",ans);

    return 0;
}