import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


class UnionFind:
    def __init__(self,n):
        self.par = [i for i in range(n+1)]  # 親のノード番号
        self.rank = [0]*(n+1)

    def find(self,x):  # xの根のノード番号
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def same_check(self,x,y):  # x,yが同じグループか否か
        return self.find(x) == self.find(y)

    def unite(self,x,y):  # x,yの属するグループの併合
        x = self.find(x)
        y = self.find(y)
        if self.rank[x] < self.rank[y]:
            x,y = y,x
        if self.rank[x] == self.rank[y]:
            self.rank[x] += 1
        self.par[y] = x


N = I()

if N == 0:
    print(1)
    exit()

XY = [None]+[tuple(MI()) for _ in range(N)]


def dist(A,B):
    ax,ay = A
    bx,by = B
    return ((ax-bx)**2+(ay-by)**2)**.5


UF = UnionFind(N)
for i in range(1,N):
    for j in range(i+1,N+1):
        if dist(XY[i],XY[j]) <= 10:
            UF.unite(i,j)

ans = 0
for i in range(1,N):
    for j in range(i+1,N+1):
        if UF.same_check(i,j):
            ans = max(ans,dist(XY[i],XY[j]))

print(2+ans)