import math
r=int(input())
if(r>0):
print(round(2*math.pi*r,2))
else:
print("Error")
for input=0.4
it showing error but i want to print circumberence
import math
r=int(input())
if(r>0):
print(round(2*math.pi*r,2))
else:
print("Error")
for input=0.4
it showing error but i want to print circumberence