#include <bits/stdc++.h> using namespace std; const double PI=3.14159265358979; inline double calArea(double radius) { return PI*radius*radius; } int main() { double r=3.0; double area=calArea(r); cout<<area<<endl; return 0; }
#include <bits/stdc++.h> using namespace std; const double PI=3.14159265358979; inline double calArea(double radius) { return PI*radius*radius; } int main() { double r=3.0; double area=calArea(r); cout<<area<<endl; return 0; }