title: Is longest possibly non-simple path in NP?
body: <p>I know that the following problem is in NP-HARD: Given a simple graph G=(V,E), two vertices v, v' in V, an integer B, and a non-negative length function len: E-> Z+, is there a <b>simple</b> path from v to v' with length less than B?</p>
  
  <p>My question is: Given the same conditions as before, if we are interested in finding the longest <b>not necessarily simple</b> path in G from vertex v to v', is the problem still in NP-HARD? </p>
  
  <p>Note: I've tried to reduce hamilton-path to it, but I'm still not able to prove whether
  there's a problem in NP reducible to this one I'm mentioning. I've also looked up in Garey &amp; Johnson but I haven't found anything.</p>
  
  <p>I would please like a little hint to prove if this problem is NP-HARD.
  Thanks in advance!</p>