n=int(input())
q=[]
for _ in range(2):
  x=[0]*n
  y=[0]*n
  for i in range(n):
    x[i],y[i]=map(float,input().split())
  gx=sum(x)/n
  gy=sum(y)/n
  q+=[max(((x[i]-gx)**2+(y[i]-gy)**2)**0.5 for i in range(n))]
print(q[1]/q[0])