062_lichangyi 2020-11-28 14:30:17 12 返回题目
#include <bits/stdc++.h> using namespace std; int main() { double a; cin >> a; cout << fixed << setprecision(6) << 2 * a * 3.14159 << endl; cout << fixed << setprecision(6) << a * a * 3.14159; return 0; }
