import java.util.HashSet;
import java.util.Scanner;
public class Kattis {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String[] line = sc.nextLine().split(" ");
int parts = Integer.parseInt(line[0]);
int days = Integer.parseInt(line[1]);
HashSet<String> hs = new HashSet<>();
for (int i = 0; i < days; i++) {
String currLn = sc.nextLine();
hs.add(currLn);
if (hs.size() == parts) {
System.out.println(i + 1);
break;
}
if(i == days-1){
System.out.println("paradox avoided");
}
}
}
}