N=int(input())

XY=[tuple(map(int,input().split())) for i in range(N)]

# UnionFind

Group = [i for i in range(N+1)] # グループ分け
Nodes = [1]*(N+1) # 各グループのノードの数

def find(x):
    while Group[x] != x:
        x=Group[x]
    return x

def Union(x,y):
    if find(x) != find(y):
        if Nodes[find(x)] < Nodes[find(y)]:
            
            Nodes[find(y)] += Nodes[find(x)]
            Nodes[find(x)] = 0
            Group[find(x)] = find(y)
            
        else:
            Nodes[find(x)] += Nodes[find(y)]
            Nodes[find(y)] = 0
            Group[find(y)] = find(x)

for i in range(N):
    x,y=XY[i]
    for j in range(i+1,N):
        z,w=XY[j]

        if (x-z)**2+(y-w)**2<=100:
            Union(i,j)

MAX=0

for i in range(N):
    x,y=XY[i]
    for j in range(i+1,N):
        z,w=XY[j]

        if find(i)==find(j):
            MAX=max(MAX,(x-z)**2+(y-w)**2)

if N!=0:
    print(MAX**(1/2)+2)
else:
    print(1)