import math
N=int(input())
d=[]
xs,ys=0,0
for _ in range(N):
    x,y=map(int,input().split())
    xs+=x
    ys+=y
    d.append((x,y))
l=0
for i in range(N):
    l+=math.sqrt((d[i][0]-xs/N)**2+(d[i][1]-ys/N)**2)
l/=N
d2=[]
zs,ys=0,0
for _ in range(N):
    z,w=map(int,input().split())
    zs+=z
    ys+=w
    d2.append((z,w))
l2=0
for i in range(N):
    l2+=math.sqrt((d2[i][0]-zs/N)**2+(d2[i][1]-ys/N)**2)
l2/=N
print(l2/l)