package algorithm;

import java.io.*;

import java.util.*;

public class TopologySortTest {

static class Node {

int vertex;

Node link;

Node(int vertex, Node link) {

this.vertex = vertex;

this.link = link;

}

}

static int N, M;

static int[] inDegree;

static Node[] adjList;

public static void main(String[] args) throws Exception {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

StringTokenizer st = new StringTokenizer(br.readLine(), " ");

N = Integer.parseInt(st.nextToken());

M = Integer.parseInt(st.nextToken());

adjList = new Node[N+1];

inDegree = new int[N+1];

int from, to;

for (int i = 0; i < M; i++) {

st = new StringTokenizer(br.readLine(), " ");

from = Integer.parseInt(st.nextToken());

to = Integer.parseInt(st.nextToken());

adjList[from] = new Node(to, adjList[from]);

inDegree[to]++;

}

ArrayList<Integer> list = topologySort();

if (list.size() == N) {

for (int v: list)

System.out.print(v+" ");

System.out.println();

} else {

System.out.println("cycle");

}

br.close();

}

static ArrayList<Integer> topologySort() {

ArrayList<Integer> orderList = new ArrayList<>();

Queue<Integer> queue = new ArrayDeque<>();

for (int i = 1; i <= N; i++) {

if (inDegree[i] == 0) queue.offer(i);

} // 진입차수가 0인 정점 큐에 넣기

while (!queue.isEmpty()) {

int cur = queue.poll();

orderList.add(cur);

// 현재 정점 기준으로 인접정점 처리

for (Node temp = adjList[cur]; temp != null; temp = temp.link) {

if (--inDegree[temp.vertex] == 0)

queue.offer(temp.vertex);

}

}

return orderList;

}

}