#danglam228
C++:

#include<bits/stdc++.h>

using namespace std;

float R, CV, DT, n=3.14;

int main(){

      cin>>R;

      CV=2*n*R;
      DT=n*R*R;

      cout<<fixed<<setprecision(1)<<CV<<endl;
      cout<<fixed<<setprecision(1)<<DT<<endl;

       return 0;

}

\begin{array}{c} \color{#db1616}{\texttt{#Khoadang09}} \end{array}
`@`$\texttt{C++: }$

#include <iostream>
#include <iomanip>
#define eol "\n"
#define int long long
#define buff ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
const double pi = 3.14;
using namespace std;
signed main(){
    buff;
    double r; cin >> r;
    cout << fixed << setprecision(1) << r * 2 * pi << eol << r * r * pi;
}