幼儿园杠把子
牛牛学圆
http://www.nowcoder.com/questionTerminal/7c2fe3592919436690bc8cea190d71cd
include
include
using namespace std;
int main()
{
double pi=3.14159;
double r;
cin>>r;
double s,l;
cout<<fixed<<setprecision(6);
cout<<2pir<<endl;
cout<<pirr;
return 0;
}
