title: Std Pair Initialization
body: <p>This is my first time working with pairs, totally confused. 
  How to initialize a pair as to insert it in the map?<br>
  Should I include some standard library for this?</p>
  
  <pre><code>#include &lt;string&gt;
  #include &lt;map&gt;
  using namespace std;
  class Roads
  {  
   public:  
    map&lt; pair&lt;string,string&gt;, int &gt; Road_map; 
    void AddRoad( string s, string d )
         { int b = 2 ; Road_map.insert( pair&lt;s,d&gt;, b) ; }  //pair&lt;s,d&gt; is wrong here.
  
   };  
  </code></pre>