The area of the circle is defined as **A = π . R ^{2}**, having

**π**as

**3.14159**.

Calculate the area using the formula given in the problem description.

## Input

Read the variable **R** (double precision), that is the radius of the circle.

## Output

Print the variable **A**, rounded to four decimal digits.

Sample Inputs | Sample Outputs |

2.00 | A=12.5664 |

100.64 | A=31819.3103 |

150.00 | A=70685.7750 |

# Solution:

#include<iostream>

#include <iomanip>

using namespace std;

int main(){

double R, A, pi;

pi=3.14159;

cin>>R;

A=pi*(R*R);

cout<<“A=”<<fixed<<setprecision(4)<<A<<endl;

return 0;

}

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