python题解：

pi = 3.14159
r = float(input())
print(2 * pi * r)
print(r ** 2 * pi)

C++题解：

#include<bits/stdc++.h>
using namespace std;
const double pi = 3.14159;
int main(){
    double r;
    cin >> r;
    cout << 2 * pi * r << endl;
    cout << pow(r, 2) * pi << endl;
    return 0;
}