import sequtils,strutils,math

type
    unionfindtree[I : static[int]] = array[I,int]

proc find(U : unionfindtree; a : int, b :int): bool=
    var
        s = a
        t = b
    while s != U[s]:
        s = U[s]
    while t != U[t]:
        t = U[t]
    return s == t
    
proc union(U : var  unionfindtree; a : int ; b : int)=
    if U.find(a,b):
        return
    var
        s = a
        t = b
        t2 : int
    while s != U[s]:
        s = U[s]
    while t != U[t]:
        t2 = U[t]
        U[t] = s
        t = t2
    U[t] = s
proc root(U : unionfindtree, a :int):int=
    var
        s = a
    while s != U[s]:
        s = U[s]
    return s

proc distance(a,b,c,d : int): float64 =
    var
        A = a.float64 - c.float64
        B = b.float64 - d.float64
    return sqrt(A * A + B * B)

var
    N = stdin.readline.parseInt
    D : array[1000,array[1000,float64]]
    P : array[1000,array[2,int]]
    UT : unionfindtree[1000]
    x,y : int
    
for i in 0..<1000:
    UT[i] = i
    
    
for n in 0..<N:
    (x,y) = stdin.readline.split.map(parseInt)
    P[n] = [x,y]
    for m in 0..<n:
        var d = distance(x,y,P[m][0],P[m][1])
        D[n][m] = d
        D[m][n] = d
        if d <= 10.00001:
            UT.union(m,n)
var memo : tuple[id1,id2 : int; dis : float64]
for n in 0..<N:
    for m in 0..<n:
        if UT.find(n,m) and memo.dis < D[n][m]:
            memo = (n,m,D[n][m])
if N > 0:
    echo memo.dis + 2
else:
    echo 1