t = [int(x) for x in input().split()]
import math
c1 = math.sqrt((t[2]-t[0])**2+(t[3]-t[1])**2)
c2 = math.sqrt((t[4]-t[0])**2+(t[5]-t[1])**2)
c3 = math.sqrt((t[4]-t[2])**2+(t[5]-t[3])**2)
print('%.2f'%(c1+c2+c3))