text: N = int(input())
  obs = [[int(a) for a in input().split()] for _ in range(N)]
  fastest = 0
  
  for i in range(len(obs) - 1):
  	a, b = obs[i], obs[i + 1]
  	time = abs(b[0] - a[0])
  	dist = abs(a[1] - b[1])
  	speed = dist / time
  	if speed > fastest:
  		fastest = speed
  print(round(fastest, 2))