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 (Python):
def sep():
    return map(int,input().strip().split(" "))
def lis():
    return list(sep())


r=int(input())
print((2*22*r)/7)

Solution (Python):
R = int(input())
import math
print(2 * math.pi * R)

Solution (Python):
print(float(input())*2*3.14159265)

Solution (Python):
import math
p=math.pi
r=int(input())

print(2*r*p)

Solution (Python):
import math

r = int(input())
print(2*r*math.pi)

Solution (Python):
r=int(input())
print(2*3.14*r)

Solution (Python):
import math
print(2*math.pi*int(input()))

Solution (Python):
import numpy as np
r=int(input())
print(2*np.pi*r)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
a=int(input())
print(2*3.1416*a)

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
r = int(input())
print(2*3.14*r)

Solution (Python):
from math import pi
print(int(input())*2*pi)

Solution (Python):
import math

R = int(input())
print(R * 2 * math.pi)

Solution (Python):
a = int(input())

n = 3.141592


print((a + a) * n)

Solution (Python):
import math
R=float(input())
r=2*math.pi*R
print(r)

Solution (Python):
import math
r = int(input())

print(math.pi*2*r)

Solution (Python):
import sys
def input():
  return sys.stdin.readline().rstrip()

from math import *

R=float(input())
print("{:.10f}".format(2*R*pi))

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import sys
import math

R = int(input())

print(2 * math.pi * R)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import math

print(int(input()) * 2 * math.pi)

Solution (Python):



r = int(input())

ans = r * 2 * 3.14159265359
print(ans)

Solution (Python):
R=int(input())
print(R*2*3.141592)

Solution (Python):
R = int(input())
print(2 * R * 3.1415926535)

Solution (Python):
import math
r = int(input())
print(math.pi*r*2)

Solution (Python):
import math

R = int(input())
print (2 * R * math.pi)

Solution (Python):
import math
r=float(input())
print(2*r*math.pi)

Solution (Python):
import sys
import math


def solve():
    readline = sys.stdin.buffer.readline
    mod = 10 ** 9 + 7
    r = int(readline())
    print(r * 2 * math.pi)


if __name__ == '__main__':
    solve()

Solution (Python):
import numpy

print(int(input())*2*numpy.pi)

Solution (Python):
R = int(input())
L = 2*R*3.141592
print(L)

Solution (Python):
import math
r=int(input())
ans_for=2*math.pi*r
print(float(ans_for))

Solution (Python):
r = int(input())
import math 
ans = 2 * math.pi * r
print(ans)

Solution (Python):
import math 
r = int(input())

ans = 2 * r * math.pi
print(ans)

Solution (Python):
R = int(input())
double = 2 * R

print(double * 3.14)

Solution (Python):
import numpy as np
R=int(input())
circle=float(R*2*np.pi)
print(circle)

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
def resolve():
    pi = 3.14159265
    r = int(input())
    print(2*r*pi)
resolve()

Solution (Python):

import math
math.pi

R = int(input())
print(2*R*math.pi)

Solution (Python):
from decimal import Decimal

r = int(input())
pie = Decimal('3.14159')

print(2 * pie * r)

Solution (Python):
import math
r = int(input())

print(2*r*math.pi)

Solution (Python):
import math
R=int(input())
print(2*math.pi*R)

Solution (Python):
import math
R = int(input())
print(2*math.pi*R)

Solution (Python):
import numpy as np

p = np.pi
r = int(input())
print(2*p*r)

Solution (Python):
import math

print(int(input()) * 2 * math.pi)

Solution (Python):
import math
R = int(input())
ans = 2.0*math.pi*R
print(ans)

Solution (Python):
import numpy as np

R = int(input())

print(R * 2 * np.pi)

Solution (Python):
r = int(input())

print(r * 3.1416 * 2)

Solution (Python):
import math
print(int(input()) * math.pi * 2)

Solution (Python):
r = int(input())
import math
print(2 * r * math.pi)

Solution (Python):

from sys import stdin, stdout



def input():
	a = stdin.readline()
	if a[-1] == "\n": a = a[:-1]
	return a
def print(*argv, end="\n", sep=" "):
	n = len(argv)
	for i in range(n):
		if i == n-1: stdout.write(str(argv[i]))
		else: stdout.write(str(argv[i]) + sep)
	stdout.write(end)

mod = 10**9+7
def lcm(x, y): return (x * y) / (gcd(x, y))
def fact(x, mod=mod):
	ans = 1
	for i in range(1, x+1): ans = (ans * i) % mod
	return ans
def arr2D(n, m, default=0):
	lst = []
	for i in range(n): temp = [default] * m; lst.append(temp)
	return lst
def sortDictV(x): return {k: v for k, v in sorted(x.items(), key = lambda item : item[1])}

from math import pi
def solve(n):
	return 2 * pi * n

n = int(input())
print(solve(n))

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
import numpy as np
R = int(input())
print(2 * R * np.pi)

Solution (Python):
r = int(input())
print(2*r*3.14159)

Solution (Python):
R = int(input())
import math
pi = math.pi
print(2 * pi * R)

Solution (Python):
import math
r=int(input())

print(2*math.pi*r)

Solution (Python):
import math

R = int(input())

p = math.pi
print(2 * p * R)

Solution (Python):
import math

r = int(input())

print(2*math.pi*r)

Solution (Python):
import math

R = int(input())

print(2 * R * math.pi)

Solution (Python):
import math

R = int(input())

print(R*2*math.pi)

Solution (Python):
import math
R = int(input())
print(2 * R * math.pi)

Solution (Python):
import math
radius=int(input())

print(2*math.pi*radius)

Solution (Python):
from math import pi

r = int(input())

print(2*pi*r)

Solution (Python):

import math


def solve(R: int):
    return 2 * math.pi * R


def main():
    R = int(input())
    answer = solve(R)
    print(answer)


if __name__ == "__main__":
    main()

Solution (Python):
n = int(input())

print(n*6.28318)

Solution (Python):
import sys
import math

R = int(input())
print(2*R*math.pi)

Solution (Python):
import math

R = int(input())

print(2 * math.pi * R)

Solution (Python):
R = int(input())
print(2 * 3.14 * R)

Solution (Python):
import math
n = int(input())
print(2 * n * math.pi)

Solution (Python):
pi = 3.14159265358

r = input()
r = int(r)

l = 2*r* pi

print(l)

Solution (Python):
import math
def main():
    r = int(input())
    print(math.pi *r *2)

if __name__ == "__main__":
    main()

Solution (Python):
import numpy as np
R=int(input())
print(2*R*np.pi)

Solution (Python):
r = int(input())

print(2 * r * 3.1415)

Solution (Python):
print(int(input())*6.3)

Solution (Python):
print(int(input())*6.28)

Solution (Python):
print(int(input())*6.283)

Solution (Python):
print(int(input())*6.2832)

Solution (Python):
import math

r = int(input())
print(math.pi * r * 2)

Solution (Python):
r = int(input())
print(r * 2 * 3.14)

Solution (Python):
import math


def main():
    R = int(input())
    print(math.pi*2.0*R)


main()

Solution (Python):
R = int(input())

print(2 * R * 3.14)

Solution (Python):
import math
print(math.pi*int(input())*2)

Solution (Python):
import math

R = int(input())

print(2 * R * math.pi)

Solution (Python):



"""






















using namespace std;

using int64 = long long;




int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  const double pi = acos(-1);
  int r; cin >> r;
  cout << fixed << setprecision(17) << 2 * pi * r << endl;

  return 0;
}

"""

import base64
import subprocess


exe_bin = "e??420s

exe_bin = base64.b85decode(exe_bin)

with open("./kyomu", 'wb') as f:
    f.write(exe_bin)

subprocess.run(["chmod +x ./kyomu"], shell=True)
subprocess.run(["./kyomu"], shell=True)

Solution (Python):
import math

R = int(input())

print (2*R*math.pi)

Solution (Python):
import math
print(int(input()) * math.pi * 2)

Solution (Python):
print(int(input())*6.3)

Solution (Python):
from math import pi


def main():
    R = int(input())
    print(2*pi*R)


if __name__ == '__main__':
    main()

Solution (Python):
R = int(input())
ans = 2 * R * 3.14159
print(ans)

Solution (Python):
r = int(input())
print(2*r*3.14)

Solution (Python):
ri = [int(v) for v in input().split()]

R, *_ = ri

print(2*3.14*R)

Solution (Python):
r = int(input())
print(r*6.2831)

Solution (Python):
import math

r = int(input())
print(2*r*math.pi)

Solution (Python):
r=float(input())
print(r*3.14159*2)

Solution (Python):
from math import pi
r = int(input())
print(r * 2 *pi)

Solution (Python):
from math import pi
R = int(input())
print(R*pi*2)

Solution (Python):
r = int(input())
print(2*r*3.14)

Solution (Python):
from math import pi
r = int(input())

print(2*r*pi)

Solution (Python):
import math
R = int(input())
print(math.pi * 2 * R)

Solution (Python):
import math 

r =int(input())
print(r*2*math.pi)

Solution (Python):
import math
R = int(input())
print(math.pi * 2 * R)

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
import math

R = int(input())
print(math.pi*R*2)

Solution (Python):
from math import pi

R = int(input())

print(2*R*pi)

Solution (Python):
from math import pi

R = int(input())

print(2 * pi * R)

Solution (Python):
import math
r = int(input())

print(math.pi*r*2)

Solution (Python):
print(int(input())*3.141592*2)

Solution (Python):
import math
R = int(input())
 
print(2*math.pi*R)

Solution (Python):
r = int(input())
print(r * 2 * 3.14)

Solution (Python):
import math
r=int(input())

ans=2*math.pi*r

print(ans)

Solution (Python):
print(float(input())*2*3.1415)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
import math

r = int(input())

print(2 * r * math.pi)

Solution (Python):
import math
R=int(input())
print(2*R*math.pi)

Solution (Python):
import math
R = int(input())
o = R*2*math.pi
print(o)

Solution (Python):
import math
R=int(input())
print(R*2*math.pi)

Solution (Python):
import math

R = int(input())
print(2*R*math.pi)

Solution (Python):
import math

R = int(input())
print(2 * R * math.pi)

Solution (Python):
r=int(input())
ans=2*r*3.141592
print(ans)

Solution (Python):
import math

R = int(input())
print(2 * math.pi * R)

Solution (Python):
r=int(input())
print(2*r*3.1415)

Solution (Python):
r=int(input())
print(2*r*3.1415)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
import math
R = int(input())
print(R * 2 * math.pi)

Solution (Python):
import math

r = int(input())

print(2*r*math.pi)

Solution (Python):
print(2*3.14159*int(input()))

Solution (Python):
from math import pi
def readinput():
    r=int(input())
    return r

def main(r):
    return 2*pi*r

if __name__=='__main__':
    r=readinput()
    ans=main(r)
    print(ans)

Solution (Python):
def resolve():
    import math
    print(2*math.pi*int(input()))

if '__main__' == __name__:
    resolve()

Solution (Python):
import math
 
R = int(input())
ans = R * 2 * math.pi
print(ans)

Solution (Python):
n=int(input())
print(2*3.14*n)

Solution (Python):
import math
R = int(input())

print(2*math.pi*R)

Solution (Python):
R = int(input())
print(R * 6.28318530717958623200)

Solution (Python):
from math import pi


def main():
    S = int(input())

    print(2 * pi * S)


if __name__ == "__main__":
    main()

Solution (Python):
import math
r=int(input())
print(2*r*math.pi)

Solution (Python):
r = int(input())
pi = 3.141593

print(r * 2 * pi)

Solution (Python):
import math
p=math.pi
R=int(input())
print(2*p*R)

Solution (Python):
r = int (input ())
print (r*2*3.1415)

Solution (Python):
import math
R = int(input())
pi = math.pi
ans = 2*R * pi
print(ans)

Solution (Python):
import math
n = int(input())
print(math.pi*n*2)

Solution (Python):
import math
R=int(input())
p=math.pi
print(R*2*p)

Solution (Python):
R = int(input())
ans = 2*R*3.14159265357989
print(ans)

Solution (Python):
r = int(input())
print(2*r*3.1415926535)

Solution (Python):
n=int(input())
print(2*3.14159*n)

Solution (Python):
r = int(input())
print(r * 2 * 3.14)

Solution (Python):
import math
r = int(input())
print(2 * math.pi * r)

Solution (Python):
import math

r = int(input())
print(2*math.pi*r)

Solution (Python):
import math
print(2*(math.pi)*int(input()))

Solution (Python):
import math
R = int(input())
print(R * 2 * math.pi)

Solution (Python):
R = int(input())

print((R * 2) * 3.14)

Solution (Python):
import math
print(int(input()) * 2 * math.pi)

Solution (Python):
from math import pi
 
R = int(input())
 
print(2 * R * pi)

Solution (Python):
import math
r = int(input())
ans = 2*r*math.pi
print(ans)

Solution (Python):
R=int(input())
print(2*R*3.1415926)

Solution (Python):
from math import pi

R = int(input())

print(2 * R * pi)

Solution (Python):
x=int(input())
import math
print(math.pi*x*2)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import math
R=int(input())
pi=math.pi
print(2*pi*R)

Solution (Python):
from math import *
s=0
n=int(input())
print(2*pi*n)

Solution (Python):
import math
a = int(input())
print(str(2*a*math.pi))

Solution (Python):
from math import pi
r = int(input())
print(2*r*pi)

Solution (Python):




n = int(input())
from math import pi
print(pi* (n*2))

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
import math

r = float(input())
pi = math.pi

print(2 * r * pi)

Solution (Python):
import math
r=int(input())
print(2*r*math.pi)

Solution (Python):
r = int(input())
print(2 * r * 3.14)

Solution (Python):
import math

r=int(input())
print(2*math.pi*r)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
from math import pi
x=float(input())
ans=2*pi*x
print(ans)

Solution (Python):
r = int(input())
print(r*2*3.14159)

Solution (Python):

import math
r=int(input())
print(2*math.pi*r)

Solution (Python):
import numpy as np
R = int(input())
print(2 * R * np.pi)

Solution (Python):
r = int(input())
print(r*2*3.14)

Solution (Python):
num=int(input())
print(3.14159265359*num*2)

Solution (Python):
from math import pi
R = int(input())
print(2*R*pi)

Solution (Python):
import math
r = int(input())

print(2 * r * math.pi)

Solution (Python):
import math
r = int(input())

print(2 * r * math.pi)

Solution (Python):
r = int(input())
print(2*r*3.1415926535)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):

import math
R = int(input())
print(2*math.pi*R)

Solution (Python):
import math
r = int(input())
print(float(r*2*(math.pi)))

Solution (Python):
import math
r=float(input())
print(r*2*math.pi)

Solution (Python):
from math import pi

print(int(input()) * 2 * pi)

Solution (Python):
import numpy as np
r = int(input())
print(2*r*np.pi)

Solution (Python):
import math
r = int(input())
print(r*math.pi*2)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
print(int(input())*44/7)

Solution (Python):
import math

def main():
    r = int(input())
    print(math.pi * r * 2)


if __name__ == "__main__":
    main()

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
import math
def main():
    r = int(input())
    print(r * math.pi * 2)
main()

Solution (Python):
def solve():
    import math
    R = int(input())
    print(2*R*math.pi)

if __name__ == "__main__":
    solve()

Solution (Python):
r=float(input())

print(2.0*3.14*r)

Solution (Python):
print(str(int(input())*6.28318530717958623200))

Solution (Python):
r = int(input())
print(2 * r * 3.1415926535897932)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
r = int(input())
print(r * 2 * 3.14)

Solution (Python):
r = int(input())
print(r * 2 * 3.14159)

Solution (Python):
print(int(input())*2*3.14)

Solution (Python):
import math

r=int(input())
print(2*math.pi*r)

Solution (Python):
x = int(input())
print(2*x*3.14)

Solution (Python):
R=int(input())
print(2*3.14*R)

Solution (Python):

R = int(input())
print(R*2 * 3.14159265)

Solution (Python):
import numpy as np

r = float(input())

ans = 2*np.pi*r

print(ans)

Solution (Python):


import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
R = int(input())

print((2 * R) * 3.14 )

Solution (Python):
import math
R = int(input())
print(2 * R * math.pi)

Solution (Python):
import math
r=int(input())
print(2*math.pi*r)

Solution (Python):
r=int(input())
print(r*2*3.14)

Solution (Python):
import math
r = int(input())
print(2 * math.pi * r)

Solution (Python):
print(int(input())*3.1415*2)

Solution (Python):
r=int(input())
import math
c=2*r*math.pi
print("{0:.6}".format(c))

Solution (Python):
r = int(input())
print((r * 2) * 3.141592)

Solution (Python):
r = int(input())
print((r * 2) * 3.141519)

Solution (Python):
import bisect,collections,copy,heapq,itertools,math,numpy,string
import sys
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())

R = I()
print(2 * math.pi * R)

Solution (Python):
import math
R = int(input())
print(R * 2 * math.pi)

Solution (Python):
pi=3.141592
r=int(input())
print(2*r*pi)

Solution (Python):
r = int(input())
p = r * 2 *3.14
print(p)

Solution (Python):
import math
R = int(input())
print(2 * R * math.pi)

Solution (Python):
import sys
read = sys.stdin.read
readlines = sys.stdin.readlines
from math import pi
def main():
    R = int(input())
    r = 2 * R * pi
    print(r)

if __name__ == '__main__':
    main()

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
import math
R = int(input())
print(2 * R * math.pi)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import math

R = int(input())

print(2*R*math.pi)

Solution (Python):
import math

n = int(input())
print(2*n*math.pi)

Solution (Python):
import math
print(2*int(input())*math.pi)

Solution (Python):
import math
r = int(input())

print(2*math.pi *r)

Solution (Python):
R = int(input())
import math
ans = R * 2 * math.pi
print(ans)

Solution (Python):
import math
R=int(input())
print(2*R*math.pi)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):

import math
import numpy
a = int(input())
print(2*a*math.pi)

Solution (Python):

import math

a = int(input())
print(2*a*math.pi)

Solution (Python):
def main():
    from math import pi

    R = int(input())

    print(2 * pi * R)


if __name__ == '__main__':
    main()

Solution (Python):
import math

r = int(input())
print(2*r*math.pi)

Solution (Python):
R = int(input())

print(R * 6.28318530717958623200)

Solution (Python):
import math
print(2*math.pi*int(input()))

Solution (Python):
import math
r = int(input())
print(math.pi*2*r)

Solution (Python):
import math

R = int(input())
print(2*R*math.pi)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
r = int(input())
print(2*r*3.1415926535)

Solution (Python):
from math import pi as pi
N=int(input().rstrip())
print(float(2.00*pi*N))

Solution (Python):
R = int(input())
import math
print(2*math.pi*R)

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
import math

R = int(input())

print(math.pi * R * 2)

Solution (Python):
import numpy as np

R = int(input())
pi = np.pi

print(2*R*pi)

Solution (Python):
import math

R = int(input())

print(2*math.pi*R)

Solution (Python):
import math
R = int(input())
print(R * 2 * math.pi)

Solution (Python):
import math

r = int(input())
p=math.pi
print(2*p*r)

Solution (Python):
R = int(input())
print(2*3.14*R)

Solution (Python):
import math
R=int(input())
print(2*math.pi*R)

Solution (Python):
r=int(input())
print(r*2*3.14159)

Solution (Python):
N = int(input())
my_result = N * 2 * 3.14159265
print(my_result)

Solution (Python):
r = int(input())
pi = 3.14159265359
print(r*2*pi)

Solution (Python):
import numpy as np

R = int(input())
print(2*np.pi*R)

Solution (Python):
import math
print(2*float(input())*math.pi)

Solution (Python):
print(int(input()) * 2 * __import__("math").pi)

Solution (Python):
from math import pi
r = int(input())
print(2*pi*r)

Solution (Python):
import math

r = int(input())

print(2 * math.pi * r)

Solution (Python):
print(3.14 * 2 * int(input()))

Solution (Python):
a=int(input())
print(a*6.283185307178)

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
import math

r = int(input())

ans = 2 * math.pi * r
print(ans)

Solution (Python):
import sys
import math


def resolve(in_):
    r = int(in_.read())
    return 2 * r * math.pi


def main():
    answer = resolve(sys.stdin.buffer)
    print(answer)


if __name__ == '__main__':
    main()

Solution (Python):
r = int(input())
print(2 * 3.1415926535 * r)

Solution (Python):
import sys, bisect, math, itertools, string, queue, copy
import numpy as np
import scipy
from collections import Counter,defaultdict,deque
from itertools import permutations, combinations
from heapq import heappop, heappush
from fractions import gcd
input = sys.stdin.readline
sys.setrecursionlimit(10**8)
mod = 10**9+7
def inp(): return int(input())
def inpm(): return map(int,input().split())
def inpl(): return list(map(int, input().split()))
def inpls(): return list(input().split())
def inplm(n): return list(int(input()) for _ in range(n))
def inplL(n): return [list(input()) for _ in range(n)]
def inplT(n): return [tuple(input()) for _ in range(n)]
def inpll(n): return [list(map(int, input().split())) for _ in range(n)]
def inplls(n): return sorted([list(map(int, input().split())) for _ in range(n)])

r = inp()
print(2 * r * math.pi)

Solution (Python):
r = int(input())

print(r * 2 * 3.1415)

Solution (Python):


import math

def main():

    R = int(input())

    ans = 2 * R * math.pi

    print(ans)


if __name__ == "__main__":
    main()

Solution (Python):
from math import pi
print(int(input())*2*pi)

Solution (Python):




































global FLAG_LOG
FLAG_LOG = False


def log(value):
    
    
    if FLAG_LOG:
        print(str(value))


def calculation(lines):
    
    R = int(lines[0])
    
    
    
    
    
    
    
    
    

    result = R * 2 * 3.141592653589793238

    return [result]



def get_input_lines(lines_count):
    lines = list()
    for _ in range(lines_count):
        lines.append(input())
    return lines



def get_testdata(pattern):
    if pattern == 1:
        lines_input = ['1']
        lines_export = [6.28318530717958623200]
    if pattern == 2:
        lines_input = ['73']
        lines_export = [458.67252742410977361942]
    return lines_input, lines_export



def get_mode():
    import sys
    args = sys.argv
    global FLAG_LOG
    if len(args) == 1:
        mode = 0
        FLAG_LOG = False
    else:
        mode = int(args[1])
        FLAG_LOG = True
    return mode



def main():
    import time
    started = time.time()
    mode = get_mode()
    if mode == 0:
        lines_input = get_input_lines(1)
    else:
        lines_input, lines_export = get_testdata(mode)

    lines_result = calculation(lines_input)

    for line_result in lines_result:
        print(line_result)

    
    
    
    
    
    
    
    
    
    
    



if __name__ == '__main__':
    main()

Solution (Python):
import math

a = int(input())
b = 2 * a * math.pi

print(str(b))

Solution (Python):
N = int(input())
print(round(N*2*3.1415,2))

Solution (Python):





r = int(input())

print (r*2*3.14)

Solution (Python):
print(float(input()) * 2.0 * 3.141592653589)

Solution (Python):


from typing import *
import itertools
import math
import sys

INF = float('inf')


def solve(R: int):
    return 2*R*math.pi


def main():

    sys.setrecursionlimit(10 ** 6)

    R = int(input())  
    print(solve(R))


if __name__ == '__main__':
    main()

Solution (Python):
import math

r = int(input())

print(r*2*math.pi)

Solution (Python):
r = float(input())

pi = 3.1415
print(r * 2 * pi)

Solution (Python):
import math
r = int(input())
print(math.pi * r*2)

Solution (Python):
import math
import sys
from collections import Counter
readline = sys.stdin.readline


def main():
    r = int(readline().rstrip())
    print(2 * r * math.pi)


if __name__ == '__main__':
    main()

Solution (Python):
r = int(input())
import math
print(2*r * math.pi)

Solution (Python):
import math


def resolve():
    import sys
    input = sys.stdin.readline
    r = int(input().rstrip())
    print(r * 2 * math.pi)



if __name__ == "__main__":
    resolve()

Solution (Python):
from math import pi

print(int(input()) * 2 * pi)

Solution (Python):
from math import pi

r = int(input())
print(2 * r * pi)

Solution (Python):
import sys
import math
R = int(input())
if not ( 1 <= R <= 100 ): sys.exit()

print((R+R) * math.pi)

Solution (Python):
import math

R = int(input())

print( 2 * R * math.pi)

Solution (Python):
import math
print(2*int(input())*math.pi)

Solution (Python):
import math
R = int(input())

print(2 * math.pi * R)

Solution (Python):

R=int(input())

print((R*2)*3.14)

Solution (Python):
import math
R=int(input())
print(math.pi*R*2)

Solution (Python):
print(6.28318530718* int(input()))

Solution (Python):
import math

print(int(input()) * 2 * math.pi)

Solution (Python):
import math
print(int(input())*math.pi*2)

Solution (Python):
r=int(input())

pi=3.141592

print(2*pi*r)

Solution (Python):
import math
print(int(input())*2*math.pi)

Solution (Python):
from math import pi

R = int(input())

print(2 * pi * R)

Solution (Python):
r=int(input())
pi=3.14159265358979323846
a=2*pi*r
print(a)

Solution (Python):
import math
print(int(input()) * math.pi * 2)

Solution (Python):
print(6.28318530717958623200*int(input()))

Solution (Python):
import math

print(int(input())*2*math.pi)

Solution (Python):
import math
r = int(input())
C = 2.0*r*float(math.pi)
print(C)

Solution (Python):
from math import pi
r = int(input())
print(2*r*pi)

Solution (Python):
R = int(input())
print(2 * R * 3.14159265359)

Solution (Python):
import math

R = int(input())
print(R*2*math.pi)

Solution (Python):
import math

R = int(input())
print(R * math.pi * 2)

Solution (Python):

import math
R = int(input())
print(2 * math.pi * R)

Solution (Python):

import math




def main():
    R = int(input())
    print(2*math.pi*R)
    

main()

Solution (Python):
print(int(input())*2*3.1415)

Solution (Python):
r = int(input())

print(r*2*3.141592653589793238462643383)

Solution (Python):
r = int(input())

import math
print(math.pi*2*r)

Solution (Python):
R = int(input())
print(R * 2 * 3.14)

Solution (Python):
import math 
def main():
  r = int(input())
  print(r * 2 * math.pi)
main()

Solution (Python):
import math
R = int(input())
print(2*math.pi*R)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):


import math

R = int(input())

print(2 * R * math.pi)

Solution (Python):
print(2*3.14*int(input()))

Solution (Python):
import math
n =int(input())
print(2*math.pi*n)

Solution (Python):
import math
print(2*math.pi*int(input()))

Solution (Python):
import math

R = int(input())

print(2*math.pi*R)

Solution (Python):
import math

r=int(input())
print(2*r*math.pi)

Solution (Python):
import math
R = int(input())
pi = math.pi

print(2*pi*R)

Solution (Python):
import math
r=float(input())

print(2*math.pi*r)

Solution (Python):
R = int(input())

import math
pi = math.pi
around = 2 * R * pi
print(around)

Solution (Python):
import math
r = int(input())
print(2*math.pi*r)

Solution (Python):
import sys
import math

sys.setrecursionlimit(10**7)
input = sys.stdin.readline

r = int(input())
print('{:.20f}'.format(2 * r * math.pi))

Solution (Python):
import math
print(int(input()) * 2 * math.pi)

Solution (Python):
import sys
from math import pi

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


def main():
    R = int(readline())

    print(2 * R * pi)

    return


if __name__ == '__main__':
    main()

Solution (Python):
import math
n = int(input())
R = 2*n*math.pi
print(R)

Solution (Python):
import math
R = int(input())

print(2 * R * math.pi)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
r = int(input())
print(2*r*3.141592)

Solution (Python):
import math
n = int(input())
print(2*n*math.pi)

Solution (Python):
R=float(input())
ans=R*2*3.141529
print("{:.3f}".format(ans))

Solution (Python):
R=int(input())
print(2*R*3.1415926)

Solution (Python):
def main():
  r = int(input())
  print(r * 2 * 3.14159265)
main()

Solution (Python):
r = int(input())
print(2*r*3.141592)

Solution (Python):
import math
R = int(input())
print(math.pi * 2 * R)

Solution (Python):
import math
r = int(input())
print(2 * math.pi * r)

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
import math
print(math.pi * int(input()) * 2)

Solution (Python):
import math
r = int(input())
print(2*r*math.pi)

Solution (Python):
from math import pi

R = int(input())

print(2*pi*R)

Solution (Python):
print(3.14159265359*2*int(input()))

Solution (Python):
import math
R = int(input())
print(2*R*math.pi)

Solution (Python):
R=int(input())
mod=3.141592
print(2*mod*R)

Solution (Python):
R=int(input())
mod=3.141592
print(2*mod*R)

Solution (Python):
import math
print(math.pi * int(input())*2)

Solution (Python):
import math

r = int(input())
print(r * 2 * math.pi)

Solution (Python):
import math
R = int(input())

print(R*2*math.pi)

Solution (Python):
print(int(input()) * 2 * 3.14)

Solution (Python):
import math

R = int(input())

print(R*2*math.pi)

Solution (Python):
import math

r = int(input())

print(2 * math.pi * r)

Solution (Python):
import math

r=int(input())



print(r*2*math.pi)

Solution (Python):
r = int(input())
print((r + r) * 3.14)

Solution (Python):
r = int(input())
print((r + r )* 3.14)

Solution (Python):
import math

r=int(input())

print(r*2*math.pi)

Solution (Python):
a = int(input())
print(2*a*3.14)

Solution (Python):
import numpy as np

r = int(input())
print(2 * r * np.pi)

Solution (Python):
r = int(input())
print( 2 * 3.14159268 * r )

Solution (Python):
R=int(input())
print(R*2*3.1415926)

Solution (Python):
import numpy as np
R = float(input())

print(2*R*np.pi)

Solution (Python):
import math
R = int(input())
print(2 * R * math.pi)

Solution (Python):
import math

r = int(input())
print(2*math.pi * r)

Solution (Python):
import numpy as np
r = int(input())
print( 2 * np.pi * r )

Solution (Python):
r = int(input())

import math

print(2 * math.pi * r)

Solution (Python):
import math

r = int(input())
print(2*math.pi*r)

Solution (Python):
import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


r = int(input())
import math
print(math.pi*r*2)

Solution (Python):
import math 
pi = math.pi
R = int(input())

print(2*R*pi)

Solution (Python):
import math
R = int(input())
print(2 * math.pi * R)

Solution (Python):
from math import pi
R = int(input())
print(2 * pi * R)

Solution (Python):
R = int(input())

print(6.28*R)

Solution (Python):
print(2*3.141592653589793238462643383279502884197169399375*int(input()))