백준 3053번 풀이

#include <iostream>
#include <cstring>
#include <algorithm>

#include <cmath>

using namespace std;

int main() {
    cin.tie(NULL);
    cin.precision(7);

    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    cout<<fixed;
    cout << atan(1)*4 *n*n<<'\n';
    cout << (double)n*n*2;

    return 0;
}