import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
/*
 * MacKenzie O'Bleness
 * Lucas Benda
 * 
 * Overbooked
 * Problem Contest #1
 */
public class Driver {

	public static void main(String args[]) throws FileNotFoundException {
		Scanner in = new Scanner(new File("overbooked.in"));
		PrintWriter out= new PrintWriter(new File("overbooked.out"));

		int numLines = in.nextInt();
		String line;
		Event[] events;

		//System.out.println(numLines);

		while (numLines != 0) {
			events = new Event[numLines];
			in.nextLine();
			for (int i = 0; i < numLines; i++) {
				line = in.nextLine();
				// System.out.println(line);
				events[i] = new Event(line);
				//System.out.println(events[i]);

			}
			
			//sort events
			Event temp;
			for (int c = 0; c < (events.length - 1); c++) {
				for (int d = 0; d < ((events.length - 1) - c); d++) {
					if(events[d].startTime>events[d+1].startTime){
						temp=events[d];
						events[d]=events[d+1];
						events[d+1]=temp;
					}
				}
			}
			boolean anyBads=false;
			for(int i=0; i<events.length-1; i++){
				anyBads= (anyBads || Event.compare(events[i], events[i+1]));
			}
			
			if(anyBads){
				out.println("conflict");
			}else{
				out.println("no conflict");
			}
			
			numLines = in.nextInt();
			//System.out.println(numLines);
		}

		// close scanners
		in.close();
		out.close();
	}

}

class Event {
	int startTime, endTime;

	public Event(String times) {
		String startS, endS;
		String[] bits = times.split("-");
		startS = bits[0];
		endS = bits[1];

		// System.out.println("Start Time: "+ startS+ " End Time: "+ endS);
		startTime=convert(startS);
		endTime=convert(endS);
	}

	private int convert(String time) {
		String min, hr;
		String[] bits = time.split(":");
		hr = bits[0];
		min = bits[1];
		
		int minInt, hrInt;
		Scanner sc=new Scanner(hr);
		hrInt=sc.nextInt();
		sc.close();
		sc=new Scanner(min);
		minInt=sc.nextInt();
		sc.close();
		
		return (hrInt*60)+minInt;
	}
	
	public String toString(){
		return "Start Time: "+ startTime + " End Time: "+ endTime;
	}
	
	public static Boolean compare(Event one, Event two){
		return (one.endTime>two.startTime);
	}
}