import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

class UnionFind:
	def __init__(self, n):
		self.par = [i for i in range(n + 1)]
		self.rank = [0] * (n + 1)
		self.size = [1] * (n + 1)

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

	def union(self, x, y):
		x = self.find(x); y = self.find(y)
		if self.rank[x] < self.rank[y]:
			if self.same_check(x, y) != True:
				self.size[y] += self.size[x]
				self.size[x] = 0
			self.par[x] = y
		else:
			if self.same_check(x, y) != True:
				self.size[x] += self.size[y]
				self.size[y] = 0
			self.par[y] = x
			if self.rank[x] == self.rank[y]:
				self.rank[x] += 1

	def siz(self, x):
		x = self.find(x)
		return self.size[x]

#処理内容
def main():
	N = int(input())
	path = []
	for i in range(N):
		X, Y = getlist()
		path.append([X, Y])

	UF = UnionFind(N)
	for i in range(N):
		for j in range(i + 1, N):
			x1, y1 = path[i]
			x2, y2 = path[j]
			if (x1 - x2) ** 2 + (y1 - y2) ** 2 <= 100:
				UF.union(i, j)

	ans = 1
	for i in range(N):
		for j in range(N):
			if UF.same_check(i, j):
				x1, y1 = path[i]
				x2, y2 = path[j]
				ans = max(ans, 2 + (((x1 - x2) ** 2) + (y1 - y2) ** 2) ** 0.5)

	print(ans)

if __name__ == '__main__':
	main()