title: How do i sort a pair increasing based on first element then decreasing based on second element?
body: <p>How do i sort  pair like this for example :</p>
  
  <p>Input :</p>
  
  <p>1 99</p>
  
  <p>2 100</p>
  
  <p>1 100</p>
  
  <p>3 400</p>
  
  <p>2 101</p>
  
  <p>output :</p>
  
  <p>1 100</p>
  
  <p>1 99</p>
  
  <p>2 101</p>
  
  <p>2 100 </p>
  
  <p>3 400</p>