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: Wrong Answer)

#include <stdio.h>

int main(void){
  int N, M, i;
  scanf("%d %d\n",&N,&M);
  int A[M];
  for(i=1;i<=M;i++){
    scanf("%d,",&A[i]);
  }
  
  for(i=1;i<=M;i++){
    N=N-A[i];
  }
  
  if(N<0){
    printf("-1\n");
  }else{
    printf("%d\n",N);
  }
}