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 C (GCC 9.2.1) (judge verdict: Runtime Error)

#include<stdio.h>
int main()
{
    int vacation,assignment,i,arr[20],sum=0,ans;
    scanf("%d %d",&vacation,&assignment);
    for(i=0;i<assignment;i++)
    {
        scanf("%d",&arr[i]);
        sum=sum+arr[i];
    }
    ans=vacation-sum;
    if(ans<0)
    {
        printf("%d",-1);
    }
    else
    {
        printf("%d",ans);
    }
return 0;
}