import java.io.*; import java.util.*; /** * Iterate over all members that ever read a message and * track the index of the message that each of those members * last sent. * Complexity O(m^2). * * @author Finn Lidbetter */ public class unread_finn { public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String[] s = br.readLine().split(" "); int n = Integer.parseInt(s[0]); int m = Integer.parseInt(s[1]); int[] arr = new int[m]; HashSet usedMembers = new HashSet<>(); for (int i=0; i lastIndex = new HashMap<>(); for (int member: usedMembers) { lastIndex.put(member, -1); } for (long i=0; i