title: Python regex find nth number
body: <p>For learning purposes I am doing some regex challenges from <em>CodeFights</em>. Now they have very specific rules in what to change to get the correct result. I solved the puzzle using a different method and I can't wrap my head around how they want me to do it.</p>
  
  <p><strong>Q:</strong> return the nth number of a giving string not leaded by zero's</p>
  
  <p><strong>Example</strong></p>
  
  <pre><code># I can only change ... to solve it
  # def nthNumber_asked(s, n):
  #    pattern = ...
  #    return re.match(pattern, s).group(1)
  
  # How I solved it
  def nthNumber_mine(s, n):
      return re.findall(r'(0*)([0-9]+)', s)[n-1][1]
  
  s1 = "8one 003number 201numbers li-000233le number444"
  s2 = "LaS003920tP3rEt4t04Yte0023s3t"
  
  print(nthNumber_mine(s1, 4)) # Expected outcome = 233
  print(nthNumber_mine(s2, 4)) # Expected outcome = 4
  </code></pre>