C # implementation of the above approach
using System ; using System . Collections . Generic ; class GFG { public class store : IComparer < KeyValuePair < int , int > > { public int Compare ( KeyValuePair < int , int > x , KeyValuePair < int , int > y ) { if ( x . Key != y . Key ) { return x . Key . CompareTo ( y . Key ) ; } else { return x . Value . CompareTo ( y . Value ) ; } } }