#yuki94
import sys

class Unionfind:
 def __init__(self,N):
  self.par=[-1]*N
    
 def root(self,x):
  if self.par[x]<0:
   return x
        
  self.par[x]=self.root(self.par[x])
  return self.par[x]
    
 def find(self,x,y):
  return self.root(x)==self.root(y)

 def unite(self,x,y):
  rx,ry=self.root(x),self.root(y)
        
  if rx!=ry:
   rx_num,ry_num=-self.par[rx],-self.par[ry]
            
   if rx_num>ry_num or (rx_num==ry_num and rx<ry):
    self.par[rx]+=self.par[ry]
    self.par[ry]=rx
   elif ry_num>rx_num or (rx_num==ry_num and ry<rx):
    self.par[ry]+=self.par[rx]
    self.par[rx]=ry

n=int(raw_input())

if n==0:
 print 1
 sys.exit()

uf=Unionfind(n)

l=[]
for i in range(n):
 l.append(map(int,raw_input().split()))

for i in range(n):
 for j in range(n):
  x1,y1=l[i]
  x2,y2=l[j]
  if (x1-x2)**2+(y1-y2)**2<=100:
   uf.unite(i,j)

res=0
for i in range(n):
 for j in range(n):
  if uf.find(i,j):
   x1,y1=l[i]
   x2,y2=l[j]
   res=max(res,(x1-x2)**2+(y1-y2)**2)

print 1.0*res**0.5+2