Problem:
Score : 100 points

Problem Statement

Print the circumference of a circle of radius R.

Constraints

1 \leq R \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

R

Output

Print the circumference of the circle.
Your output is considered correct if and only if its absolute or relative error from our answer is at most 10^{-2}.

Sample Input 1

1

Sample Output 1

6.28318530717958623200

Since we accept an absolute or relative error of at most 10^{-2}, 6.28 is also an acceptable output, but 6 is not.

Sample Input 2

73

Sample Output 2

458.67252742410977361942

Solution in Java (OpenJDK 1.8.0) (judge verdict: Accepted)

public class Main {
    public static void main(String[] args) {
        int value = Integer.parseInt(readLine(255));
        System.out.printf("%f",(2*Math.PI*value));
    }

    public static  String readLine(int maxLen){
        int[] holder = new int[maxLen];
        int counter =0, reader =1;

        try{
            while(counter < maxLen){
                reader = System.in.read();
                if(reader <0 || (reader =='\n'))break;
                holder[counter++] = reader;
            }
        }catch(Exception ex){
            return (null);
        }

        if(counter ==0 && reader <0)return (null);
        return new String(holder,0,counter);
    }
}