from math import*
def dis(a, b, c, d):
    return sqrt((a-b)**2+(c-d)**2)
def main():
    x1,y1=map(int,input().split())
    x2,y2=map(int,input().split())
    x3,y3=map(int,input().split())
    print("{:.2f}".format((int(dis(x1,x2,y1,y2)+dis(x1,x3,y1,y3)+dis(x2,x3,y2,y3)))))
main()