暴力

#include<bits/stdc++.h>
using namespace std;
const double PI=3.14159;
int main(){
double r;
cin>>r;
printf("%.4lf",r2);
cout<<" ";
printf("%.4lf",r2PI);
cout<<" ";
printf("%.4lf",rr*PI);
cout<<" ";
return 0;
}