还行

#include <iostream>
using namespace std;

int main() {
double r; // 半径
cin >> r;
double zhijing = r * 2;
double c = r * 2 * 3.14159;
double s = r * r * 3.14159;
printf("%.4f %.4f %.4f", zhijing, c, s);
return 0;
}