min_  = 1000000000
difmax=-1000000000
cnt=0
n = STDIN.gets.split[0].to_i
0.upto(n-1) {|i| 
  n = STDIN.gets.split[0].to_i

  dif = n - min_   if(i>0)

  if n < min_
    min_ = n
  end
 
  difmax = dif if dif > difmax   if(i>0)
}
puts difmax