#include <stdio.h>
#include <stdlib.h>

struct list
{
	int info;
	struct list *next;
};
typedef struct list List;

void push(int value, List *stackTop);
int pop(List *stackTop);
int read(List **graph, const char *fileName);
void df(int current, int *visited, List **graph, List *stack, List *solution);
void topologicalSort(List **graph, int nrVertices, List *solution);

int main()
{
	FILE *out = fopen("sortaret.out", "w");
	List **graph, *solution;
	int nrVertices;
	
	solution = malloc(sizeof(List));
	nrVertices = read(graph, "sortaret.in");
	topologicalSort(graph, nrVertices, solution);
	
	for(solution = solution->next; solution; solution = solution->next)
		fprintf(out, "%d ", solution->info);
	fprintf(out, "\n");
	fclose(out);
	return 0;
}

void topologicalSort(List **graph, int nrVertices, List *solution)
{
	int *visited, i;
	List *stack;
	
	stack = malloc(sizeof(List));
	visited = calloc(nrVertices + 1, sizeof(int));
	
	stack->next = solution->next = NULL;
	
	for(i = 1; i <= nrVertices; i++)
		if(!visited[i])
		{	
			df(i, visited, graph, stack, solution);
			push(i, solution);
		}
}

void df(int current, int *visited, List **graph, List *stack, List *solution)
{
	List *c;
	visited[current] = 1;
	for(c = graph[current]; c; c = c->next)
		if(!visited[c->info])
		{
			push(c->info, stack);
			df(c->info, visited, graph, stack, solution);
			push(pop(stack), solution);
		}
}

int read(List **graph, const char *fileName)
{
	FILE *in = fopen(fileName, "r");
	List *v;
	int m, n, i;
	
	fscanf(in, "%d %d", &n, &m);
	*graph = malloc((n + 1) * sizeof(List));
	for(i = 0; i <= n; i++) graph[i] = NULL;
	for(; m ; m--)
	{
		int a, b;
		fscanf(in, "%d %d", &a, &b);
		v = malloc(sizeof(List));
		v->info = b;
		v->next = graph[a];
		graph[a] = v;
	}
	
	fclose(in);
	return n;
}

void push(int value, List *stackTop)
{
	List *c;
	c = malloc(sizeof(List));
	c->info = value;
	c->next = stackTop->next;
	stackTop->next = c;
}

int pop(List *stackTop)
{
	int value;
	if(stackTop->next)
	{
		value = stackTop->next->info;
		stackTop->next = stackTop->next->next;
	}
	else value = -1;
	
	return value;
}