n = int(input())
xy = [list(map(int, input().split())) for i in range(n)]
data=[[-1]*(10**3) for i in range(10**3)]
ans=0
if n==0:
    print(1)
    exit()

class UnionFind:
    __slots__ = ['id']

    def __init__(self, n):
        self.id = [-1] * n

    def root(self, x):
        if self.id[x] < 0:
            return x
        else:
            self.id[x] = self.root(self.id[x])
            return self.id[x]

    def find(self, x, y):
        return self.root(x) == self.root(y)

    def union(self, x, y):
        s1, s2 = self.root(x), self.root(y)
        if s1 != s2:
            if self.id[s1] <= self.id[s2]:
                self.id[s1] += self.id[s2]
                self.id[s2] = s1
            else:
                self.id[s2] += self.id[s1]
                self.id[s1] = s2
            return True
        return False

uf =UnionFind(n)
for i in range(n):
    x,y=xy[i]
    data[x][y]=i

for k in range(n):
    x,y=xy[k]
    for i in range(-10,11):
        for j in range(-10,11):
            if data[i][j]>=0:
                if (x-i)**2+(y-j)**2<=100:
                    uf.union(k,data[i][j])

for i in range(n):
    for j in range(n):
        if uf.find(i,j):
            x1,y1=xy[i]
            x2,y2=xy[j]
            ans=max(ans,(x1-x2)**2+(y1-y2)**2)
print(ans**(0.5)+2)