题解 | #牛牛学圆#
牛牛学圆
https://ac.nowcoder.com/acm/problem/21997
include<bits/stdc++.h>
using namespace std;
int main()
{
double a;
double c,s;
double pi=3.14159;
cin>>a;
c=pi2.0a;
s=piaa;
printf("%.6f\n",c);
printf("%.6f",s);
return 0;
}
