import math

A = list(map(int, input()))

B = list(map(int, input()))

#C = list(map(int, input()))

if A,B < len(3):
   print(D_1)
else:
    print(D_2)


D_1 = math.sqrt( (B[0]-A[0])**2 + (B[1]-A[1])**2 + (B[2]-A[2])**2 )

D_2 = math.sqrt( (B[0]-A[0])**2 + (B[1]-A[1])**2 )