title: "Int" multiplication in c++ with "long long" result
body: <p>I am trying to find the square of a <code>int</code>. My code looks like below:</p>
  
  <pre><code>long long sqr=0;
  int num=77778;
  sqr= num*num;
  </code></pre>
  
  <p>The result should have been <code>6049417284</code>
  But when I check the output it shows <code>1754449988</code>.
  What is the mistake I am doing? 
  <code>long long</code> should be able to store the result but why am I getting a different value?</p>