title: How to substract from dictionary value in Python?
body: <p>I must substract from dictionary values.</p>
  
  <pre><code>list1 = {'i': 1, 'k': 1, 'j': 1, 'o': 2, 'q': 1, 's': 1, 'x': 1, 'z': 1}
  string = 'ikjoosgx'
  for letter in string:
  I NEED TO DECREASE list1 key of same name as letter VALUE BY 1. DIPSIT!
  </code></pre>