#include<bits/stdc++.h>
using namespace std;
#include<queue>
const int maxn = 505;
bool mpt[maxn][maxn];
int lev[maxn];//点的入度
vector<int>v[maxn];//邻接表存储边
priority_queue<int, vector<int>,greater<int>>q;//最小元素最优先
void topo(int n)
{
	for (int i = 1;i <= n;i++)
	{
		if (!lev[i])q.push(i);
	}
	int flag = 0;
	while (!q.empty())
	{
		int now = q.top();
		q.pop();
		if (flag)printf(" %d", now);
		else printf("%d", now);
		flag++;
		for (int i = 0;i < v[now].size();i++)
		{
			int next = v[now][i];
			lev[next]--;
			if (!lev[next])q.push(next);
		}
		
	}if (flag != n)
			printf("有环，无拓扑排序");
}
int main()
{
	int n, m;
	while (scanf("%d%d", &n, &m) != EOF)
	{
		memset(mpt, 0, sizeof(mpt));
		for (int i = 1;i <= m;i++)
		{
			int a, b;
			scanf("%d%d", &a, &b);
			mpt[a][b] = 1;
		}
		for (int i = 1;i <= n;i++)
		{
			v[i].clear();
			for (int j = 1;j <= n;j++)
			{
				if (mpt[...