title: Increasing value for key which is existing in dictionary
body: <p>I'm trying to create concordance.
  I have dictionary, where key -  is word and value - is frequency of this word
  If word exist in dictionary  I need to increase value for this word.
  I'm using ContainsKey to check if word exists, bot don't understand how to increase value</p>
  
  <pre><code>    string[] words = SplitWords(lines);
  
      foreach (var  word in words)
      {
              int i = 0;
              if (!concordanceDictionary.ContainsKey(word))
              {
                  concordanceDictionary.Add(word, i);
              }
              else
              {
  
              }
              foreach (KeyValuePair&lt;string, int&gt; pair in concordanceDictionary)
              {
                  Console.WriteLine("{0}:{1}",pair.Key, pair.Value);
             }
          }
  </code></pre>