import math
a,b=map(int,input().split())
c,d=map(int,input().split())
e,f=map(int,input().split())
x=math.sqrt((a-c)**2+(b-d)**2)
y=math.sqrt((a-e)**2+(b-f)**2)
z=math.sqrt((c-e)**2+(f-d)**2)
print(format(x+y+z, ".2f"))