def far(x1,y1,x2,y2,x3,y3):
    a = ((x1-x2) ** 2 + (y1-y2) ** 2) ** 0.5
    b = ((x2-x3) ** 2 + (y2-y3) ** 2) ** 0.5
    c = ((x3-x1) ** 2 + (y3-y1) ** 2) ** 0.5
    print('%.2f'%(a+b+c))

q,w,e,r,t,y =map(int,input().split())
far(q,w,e,r,t,y)