title: Number of repeating of each letter
body: <p>Do you know how to find the number of repeating of each letter in a word in C++?
  For example the word is MISSISSIPPI.</p>
  
  <p>M - 1</p>
  
  <p>I - 4</p>
  
  <p>S - 4</p>
  
  <p>P - 2</p>