'''name = input()
age = int(input())
print("In 15 years, age of " +name+ " will be " +str(age+15))'''
'''a = int(input('a = '))
b = int(input('b = '))
print("a % b =" +str(a % b))
'''
'''a=float(input('nhập a:'))
b=float(input('nhập b:'))
print('tổng: '+ str(format(a+b,".3f")))
print('hiệu: '+ str(format(a-b,".3f")))
print('tích: '+ str(format(a*b,".3f")))
print('thương: '+ str(format(a/b,".3f")))'''
'''a = int(input())
b = int(input())
print("a + b = " +str(a + b))
print("a - b = " +str(a - b))
print("a * b = " +str(a * b))
print("a / b = " +str(format(a / b,".2f")))
print("a % b = " +str(a % b))'''

'''a = int(input())
b = int(input())
c = a
a = b 
b = c
print("after swap a = " + str(a) + ", b = " + str(b))'''
 
r = float(input())
print("Circumference = "+str(2 *3.14 * r))
e5d38ad955ad07238975c9a3be09d3668e6f2dd4
<mask token>

<mask token>
print('Circumference = ' + str(2 * 3.14 * r))

<mask token>
r = float(input())
print('Circumference = ' + str(2 * 3.14 * r))

'''name = input()
age = int(input())
print("In 15 years, age of " +name+ " will be " +str(age+15))'''
'''a = int(input('a = '))
b = int(input('b = '))
print("a % b =" +str(a % b))
'''
'''a=float(input('nhập a:'))
b=float(input('nhập b:'))
print('tổng: '+ str(format(a+b,".3f")))
print('hiệu: '+ str(format(a-b,".3f")))
print('tích: '+ str(format(a*b,".3f")))
print('thương: '+ str(format(a/b,".3f")))'''
'''a = int(input())
b = int(input())
print("a + b = " +str(a + b))
print("a - b = " +str(a - b))
print("a * b = " +str(a * b))
print("a / b = " +str(format(a / b,".2f")))
print("a % b = " +str(a % b))'''

'''a = int(input())
b = int(input())
c = a
a = b 
b = c
print("after swap a = " + str(a) + ", b = " + str(b))'''
 
r = float(input())
print("Circumference = "+str(2 *3.14 * r))