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):
import sys
from io import StringIO
import unittest
import math


class TestClass(unittest.TestCase):
    def assertIO(self, input, output):
        stdout, stdin = sys.stdout, sys.stdin
        sys.stdout, sys.stdin = StringIO(), StringIO(input)
        resolve()
        sys.stdout.seek(0)
        out = sys.stdout.read()[:-1]
        sys.stdout, sys.stdin = stdout, stdin
        self.assertEqual(out, output)

    def test_入力例_1(self):
        input = """1"""
        output = """6.28318530717958623200"""
        self.assertIO(input, output)

    def test_入力例_2(self):
        input = """73"""
        output = """458.67252742410977361942"""
        self.assertIO(input, output)


def resolve():
    r = read()
    result = think(r)
    write(result)


def read():
    return read_int(1)[0]


def read_int(n):
    return read_type(int, n, sep=' ')


def read_float(n):
    return read_type(float, n, sep=' ')


def read_type(t, n, sep):
    return list(map(lambda x: t(x), read_line().split(sep)))[:n]


def read_line(n=0):
    if n == 0:
        return input().rstrip()
    else:
        return input().rstrip()[:n]


def think(data):
    return 2 * data * math.pi


def write(result):
    print(result)


if __name__ == '__main__':
    
    resolve()

Solution (Python):
import math

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

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

Solution (Python):
r = int(input())
print(r*2*314/100)

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

r = a * 2 * 3.14

print(r)

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

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

Solution (Python):
import math

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

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

Solution (Python):
import numpy as np
r = int(input())

print(2 * np.pi * r)

Solution (Python):
from math import pi
R = int(input())
print("{}".format(2*R*pi))

Solution (Python):
r = int(input())
print(r*2*3.141)

Solution (Python):
a = int(input())
pai = 3.1415926535897932384626433832795028841971693

print(2*a*pai)

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 = input()

R = float(R)

print(2*R*math.pi)

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

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

Solution (Python):

import math 
radius = int(input())
pi = math.pi
ans = 2 * radius * pi
print(f'{ans:.020f}')

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

print(float(2*R*math.pi))

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

Solution (Python):
r = int(input())
print(2*r*3.14159265358)

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

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

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

Solution (Python):
import math

R = int(input())

print(2*R*math.pi)

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

print(R * 2 * 3.1415)

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

Solution (Python):
r = int(input())
pi = 3.1415

print(2 * pi * r)

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

print(r * 2 * 3.1415926535897932384626433)

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

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

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

Solution (Python):
import math

r = int(input())
p = math.pi

print(2*r*p)

Solution (Python):
import math

R = int(input())

print(2 * R * math.pi)

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

print(a*3.14159265358979*2)

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

Solution (Python):

import math

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

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

Solution (Python):
import math

R = int(input())

print(R * 2 * math.pi)

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

cir=2*math.pi*R

print(cir)

Solution (Python):
import math

r = int(input())

print(2*r*math.pi)

Solution (Python):
r = int(input())
if 0 <= r <= 100:
    length = 2 * r * 3.1415926535
    print(length)

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):
a = float(input())
print(a*2*3.14)

Solution (Python):
import math
r = input()
pi = math.pi
c = 2 * float(r) * pi
print(f'{c:.20f}')

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 = float(input())

print(2*math.pi*R)

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

Solution (Python):
import math

R = int(input())

circum = R * 2 * math.pi 

print(circum)

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

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

    circum = 2 * r * math.pi
    print(circum)
resolve()

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

Solution (Python):
import math

R = int(input())

print(2.0 * math.pi * R)

Solution (Python):
import math

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

Solution (Python):
import math 

r=int(input())
L=2*math.pi*r
print('{0}'.format(L))

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):
print(eval(input()+'*6.2831'))

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

print(r * 2 * 3.1415)

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

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

Solution (Python):
import math

r = int(input())

ans = 2 * r * math.pi

print(ans)

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

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

Solution (Python):
import math

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

Solution (Python):
import math
import sys
input = sys.stdin.readline


def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))
    
n = inp()

print (math.pi * 2 * n)

Solution (Python):
import math

R = int(input())

print(math.pi * 2 * R)

Solution (Python):
import numpy as np

R = int(input())

l = R * 2 * np.pi

print(str(l))

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

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

l = R * 2 * 3.1415
print(l)

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

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())
round_R = 2 * R * math.pi
print(round(round_R, 10))

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

print(math.pi * R*2)

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

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

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

print(2 * r * math.pi)

Solution (Python):
import numpy as np


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

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

Solution (Python):
from math import pi

print(2 * pi * int(input()), end='\n\r')

Solution (Python):
from math import pi

print(2 * pi * int(input()), end='\n')

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

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

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

Solution (Python):
import math

a = float(input())

print(2 * a * math.pi )

Solution (Python):
import math

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

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

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

Solution (Python):
import math
r=int(input())
a=3.14159265359
print(2*r*a)

Solution (Python):
import math
r = int(input())
x = r * math.pi * 2
n = 10
y = math.floor(x * 10 ** n) / (10 ** n)
print(y)

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

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

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

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

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

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

Solution (Python):
import math

r = int(input())

l = 2*math.pi*r

print(l)

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

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

Solution (Python):
import math

n = int(input())

print(n*2*math.pi)

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

Solution (Python):
import numpy as np
r=int(input())

print(np.pi*2.0*r)

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

import math 

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

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

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

Solution (Python):
import math

R = int(input())

print(2*R*math.pi)

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

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):
r=int(input())
print(2*r*3.1415926535237)

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):
r = int(input())
a = 2 * r * 3.141592
print(a)

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 * r * math.pi)

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

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(str(2 * R * math.pi))

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

Solution (Python):
import math

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

Solution (Python):
from math import pi

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

Solution (Python):
import math as m

r = int(input())

ans = 2 * r * m.pi
print(f'{ans:.5f}')

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

print(2*r*3.1415)

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

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

Solution (Python):
r = float(input())
print(3.14159265358979*2*r)

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

Solution (Python):
import sys
input = sys.stdin.readline

import numpy as np

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

Solution (Python):
r=int(input())
print("{}".format(r*2*3.141592))

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

Solution (Python):
import math

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

Solution (Python):
print(2.0*3.1415926535*int(input()))

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

Solution (Python):
import math
R = float(input())
L = float(2) * round(math.pi, 10) * R
print(L)

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

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

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

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

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

Solution (Python):
import sys
from collections import deque
import copy
def main():
    N = int(input())
    print(N * 6.28318530717958623200)


if __name__ == '__main__':
    main()

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

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

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

Solution (Python):
import sys
input = sys.stdin.readline

def main():
    R = int(input())
    print(6.28318530717958623200*R)


if __name__ == "__main__":
    main()

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

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

Solution (Python):
import math

r = int(input())

print(2*r*math.pi)

Solution (Python):
import numpy as np

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

        print("{}".format(2*R*np.pi))


if __name__=="__main__":
        main()

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

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

Solution (Python):
print(int(input())*6.283185307179586232)

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

print(2*R*math.pi)

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

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

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

print(2*3.14*r)

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

import math

p=math.pi

ans=2*p*R

print(ans)

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

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

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

Solution (Python):
import math

R = int(input())

print(2 * math.pi * R)

Solution (Python):
from sys import stdin, setrecursionlimit


def main():
    input = stdin.buffer.readline
    r = int(input())
    print(2 * r * 3.14)


if __name__ == "__main__":
    setrecursionlimit(10000)
    main()

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):

R=input()
R=float(R)
print(R*(6.28))

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

pi = math.pi

print(2*R*pi)

Solution (Python):
import math


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


if __name__ == '__main__':
    main()

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

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

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

Solution (Python):
import math

r = int(input())

ans = (r * 2) * math.pi

print(ans)

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

import math

l = 2*math.pi*R

print(l)

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

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

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

print(2*R*pai)

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

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

Solution (Python):
R=int(input())
print(R*2*3.141)

Solution (Python):
import math

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

Solution (Python):
import math

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

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

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

Solution (Python):
def solve(string):
    from math import pi
    return str(2 * int(string) * pi)


if __name__ == '__main__':
    import sys
    print(solve(sys.stdin.read().strip()))

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

Solution (Python):
R = int(input())
print (2*(3.141592653589793238)*R)

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

print(2*math.pi*R)

Solution (Python):
N = int(input())
pi = 3.141596535

k = 2 * N * pi
print(k)

Solution (Python):


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

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

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

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

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

print(3.141 * 2 * r)

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

Solution (Python):
import math

R = int(input())

print(round((R+R)*math.pi,3))

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

Solution (Python):
import math

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

Solution (Python):
from functools import reduce
from fractions import gcd
import math
import bisect
import itertools
import sys
sys.setrecursionlimit(10**7)
input = sys.stdin.readline
INF = float("inf")


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


if __name__ == '__main__':
    main()

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

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

Solution (Python):
import math

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

print(q)

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

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

print(2 * math.pi * R)

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

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

pi = 3.141592

print(2*pi*r)

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

Solution (Python):
import math

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

if __name__ == '__main__':
    main()

Solution (Python):
def main():
    r = int(input())
    pi = 3.141
    print(2*pi*r)

main()

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

Solution (Python):
import math

s = float(input())
t = 2 * math.pi * s
print(t)

Solution (Python):
import math

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

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

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

Solution (Python):
from sys import stdin, stdout
from collections import deque, defaultdict
import math as m

rl = lambda: stdin.readline()
rll = lambda: stdin.readline().split()
rli = lambda: map(int, stdin.readline().split())

INF, NINF = float('inf'), float('-inf')

def main():
	r = int(rl())
	print(2*m.pi*r)
	stdout.close()

if __name__ == "__main__":
	main()

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

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

print(2 * pi * N)

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

Solution (Python):
import math


def actual(r):
    return 2 * r * math.pi

r = int(input())
print(actual(r))

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

print(2*3.141592*r)

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

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

Solution (Python):
import math

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

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

Solution (Python):
import math

def circumference(r):
    return 2 * math.pi * r


r = input()
r = int(r)
res = circumference(r)
print(res)

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

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

print(2 * math.pi * r)

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

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

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

l = 2 * R * 3.14

print(l)

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

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

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

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

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

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

print(2*n*3.141592)

Solution (Python):
import math

R = int(input())

print(R * 2 * math.pi)

Solution (Python):
from math import pi

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

Solution (Python):
import numpy as np

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

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

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

Solution (Python):
a = int(input())
print("{}".format(3.141592*2*a))

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

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

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

Solution (Python):
from sys import stdin

S = float(stdin.readline().rstrip())
print(S*2*3.14)

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

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

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

Solution (Python):
import math

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

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

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

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

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

Solution (Python):
import math

r = int(input())

print(2*r*math.pi)

Solution (Python):
def ABC_163_A():
    R = int(input())
    print(3.14*2*R)


if __name__ == '__main__':

    ABC_163_A()

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

Solution (Python):
import numpy as np

R = int(input())

print(2*R*np.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):
def main():
    import sys
    input=sys.stdin.readline
    import math
    r=int(input())
    print(2*r*math.pi)
if __name__ == '__main__':
    main()

Solution (Python):
import math 

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

Solution (Python):
import math

R = int(input())

out = R * 2 * math.pi

print(out)

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

Solution (Python):
import math 

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

Solution (Python):
import numpy as np

r = int( input() )

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

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())
import math

print(2*R*math.pi)

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

print(r * 2 * 3.14)

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

import math

print(2*math.pi*R)

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

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

Solution (Python):
R = int(input())
print(2*3.14*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):
R=int(input())
import math
print(2*R*math.pi)

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

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

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

Solution (Python):
import math

R = int(input())

print("{}".format(2*R*3.14159))

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

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

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 sys
import os
import bisect, collections, copy, itertools, math, string
def I(): return int(input())
def S(): return input()
def LI(): return list(map(int, input().split()))
def LS(): return list(input().split())

def solve():
	R = I()
	r = 2 * math.pi * R
	print(r)
	
if __name__ == '__main__':
	solve()

Solution (Python):
pi=3.1415926

r=int(input())

print(2*pi*r)

Solution (Python):
import numpy as np


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


if __name__ == "__main__":
    main()

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

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

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):
R = input()

A = float(R)
print(A * 2 * 3.14)

Solution (Python):
import math

def main():
    R = input()
    X = 2 * math.pi * float(R)

    print(X)

if __name__ == '__main__':
    main()

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

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

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())
x = 2*r*math.pi

print(x)

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

Solution (Python):
a=int(input())
print(2*3.1415926538*a)

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

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

Solution (Python):
import math

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

Solution (Python):
import math

def calc_circumference(R: int) -> float:
    return 2 * math.pi * R

if __name__ == '__main__':
    R = int(input())
    res = calc_circumference(R)
    print(res)

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

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

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

Solution (Python):
import math
import sys
sys.setrecursionlimit(10**7)
input = lambda: sys.stdin.readline().strip()

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

main()

Solution (Python):
import math

r = int(input())

print(2*math.pi*r)

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

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

Solution (Python):
import math
from math import pi

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

Solution (Python):
import math
p = math.pi

r = int(input())
l = float(2 * r * p)

print(l)

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

Solution (Python):
import math


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

if __name__ == '__main__':
    solve()

Solution (Python):
R = int(input())
print(2*R*3.141592653589)

Solution (Python):


r = int(input())

print(2*3.14159265*r)

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

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

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

Solution (Python):
import math

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

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

Solution (Python):



import sys
sys.setrecursionlimit(10**7)
from pprint import pprint as pp
from pprint import pformat as pf

import math

import bisect


if __name__ == '__main__':
    r = int(input())
    ans = 2 * r * math.pi
    
    print(ans)

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

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

print(r*2*3.1415916536)

Solution (Python):
import math

pi = math.pi

R = int(input())

print(2 * R * pi)

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

print(math.pi * 2 * R)

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

Solution (Python):


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

Solution (Python):
from sys import stdin


def main():
    r = int(stdin.readline())
    print(2 * r * 3.14)


if __name__ == "__main__":
    main()

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

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

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

print(ans)

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):
import math;

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

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

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

pai = 3.14

print(2 * pai * r)

Solution (Python):
R=int(input())
print((2*R)*3.142)

Solution (Python):
import math

R = int(input())

pai = math.pi

print(2 * R * pai)

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

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

Solution (Python):
R=str(input())
length=2*3.14*float(R)
print(length)

Solution (Python):
import math

print(math.pi * float(input()) * 2.0)

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

Solution (Python):
R = int(input())
len = 2*R*3.142592
print(len)

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

Solution (Python):
print(6.283185307179586 * 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())
print(2 * math.pi * R)

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

Solution (Python):
import math

r=float(input())

L=2*math.pi*r

print(L)

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

Solution (Python):
import numpy as np

def calculate_length(radius):
    return 2.0 * radius * np.pi

if __name__ == "__main__":
    radius = int(input())
    print(calculate_length(radius))

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

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

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

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

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*3.14)

Solution (Python):
print(int(input())*6.28, end="")
for _ in range(1000000):
  print("0000000000000000000000", end="")

Solution (Python):
print(int(input())*6.28, end="")
for _ in range(100000):
  print("00000000000", end="")

Solution (Python):
import math

r=input()

print(2*float(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)