title: generate unique Long for unique String seed
body: <p>I need to generate a unique <code>Long</code> of length of 10 or more digits from String seed that can be of any length. In normal circumstances it would be not possible to do since there are more <code>String</code> permutations than <code>Long</code> can store, however i know that system will not generate more <code>Strings</code> than i can store in <code>Long</code>, how can i generate unique <code>Long</code> for each <code>String</code> in such circumstances?</p>
  
  <p>I can not use dynamic perfect hashing since is too time consuming and i can not use minimal perfect hash function since i dont want generated numbers to seqentional.</p>
  
  <p>EDIT: i can not store any information about already processed Strings, including amount of them</p>