1438 [CA1002]Circle

Description

Given a circle with radius R, please calculate the area of this circle.

Input

The input contains a real number R(0.1 <= R <= 100)

Output

Output the area of the circle in a line. The answer should be rounded to 8 digits after the decimal point.

Sample Input

0.564189583547

Sample Output

1.00000000

Hint

you can assume PI = 3.14159265358979

Submission

answer.cpp

#include<iostream>#include<iomanip>using namespace std;int main(){    double R;    cin>>R;    cout<<setprecision(8)<<fixed<<3.14159265358979*R*R<<endl;    return 0;}

Standard Answer

answer.cpp

#include <iostream>#include <iomanip>using namespace std;const double PI = 3.14159265358979;int main(){    double r; cin >> r;    cout << fixed << setprecision(8) << r * r * PI << endl;    return 0;}