// Topological Sort.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

//#include "pch.h"
#include <iostream>
#include <deque>
#include <stack>
#include <queue>
#include <fstream>
using namespace std;
ifstream fin("sortaret.in");
ofstream fout("sortaret.out");
#define MAXE 50001
struct vertex {
	int weight;
	int value;
	vertex * next;
};
class Graph {
private:
	deque<vertex *> adjacencyList;
	deque<int> degree;
	deque<bool>processed;
	deque<bool>discovered;
	stack<bool>discoveredTop;
	deque<bool>vertexDiscovered;

	int nVertices, nEdges;
	bool directed;
public:
	void initialiseGraph() {
		for (int i = 1; i <= MAXE; ++i) {
			adjacencyList.push_back(nullptr);
			degree.push_back(0);
			discovered.push_back(false);
			processed.push_back(false);
			vertexDiscovered.push_back(false);
		}
	}
	void readGraph(int nVertices, int nEdges, bool directed) {
		int x, y;
		this->nVertices = nVertices;
		this->nEdges = nEdges;
		this->directed = directed;
		initialiseGraph();
		for (int i = 1; i <= nEdges; ++i) {
			fin >> x >> y;
			insertEdge(y, x, directed);
		}
	}
	void insertEdge(int x, int y, bool directed) {
		vertex * newVertex = new vertex;
		newVertex->value = x;
		newVertex->weight = 0;
		newVertex->next = adjacencyList.at(y);
		adjacencyList.at(y) = newVertex;
		if (directed == false) {
			insertEdge(y, x, !directed);
		}
	}
	void printAdjacencyList() {
		vertex * aux;
		for (int i = 0; i <= nVertices; ++i) {
			if (adjacencyList.at(i) != nullptr)
				fout << i << " : ";
			aux = adjacencyList.at(i);
			while (aux != nullptr) {
				fout << aux->value << " ";
				aux = aux->next;
			}
			fout << endl;
		}
	}

	void topologicalSort(int v) {
		queue<int>vertices;
		queue<int>Queue;
		vertices.push(v);
		vertexDiscovered.at(v) = true;
		Queue.push(v);
		while (!vertices.empty()) {
			int x = vertices.front();
			vertices.pop();
			
			vertex * aux = adjacencyList.at(x);
			while (aux != nullptr) {
				int y = aux->value;
				if (vertexDiscovered.at(y) == false) {
					vertices.push(y);
					vertexDiscovered.at(y) = true;
					Queue.push(y);
				}
				aux = aux->next;
			}
			
		}
		while (Queue.empty() == false)
		{
			fout << Queue.front() << " ";
			Queue.pop();
		}
	}
	
};
int main()
{
	int nVertices, nEdges;
	fin >> nVertices >> nEdges;
	Graph g;
	g.readGraph(nVertices, nEdges, true);
	g.topologicalSort(1);
	return 0;
	
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

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//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file