URI - Problem 1002 - Area of a Circle

#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    double A, n=3.14159, R;

    cin >> R;

    A = n * R * R;

    cout << "A=" << fixed <<setprecision(4) << A << endl; //setting 4 digits after decimal point. needs "iomanip"

    return 0;
}