1 # include <stdio.h>
2 # include <string.h>
3 # define MAX 1000
4 int n,m,indegree[MAX];
5 int G[MAX][MAX],q[MAX];
6 void toposort()
7 {
8 int i,j,k;
9 for(i=0;i<n;)
10 {
11 for(j=1;j<=n;j++) //从最小的点开始找。
12 {
13 if(indegree[j] == 0)
14 {
15 indegree[j]--;
16 q[i++]=j;
17 for(k=1;k<=n;k++)
18 if(G[j][k])
19 indegree[k]--;
20
21 }
22 }
23 }
24 }
25 int main()
26 {
27 int i,a,b;
28 while(scanf("%d%d",&n,&m) == 2)
29 {
30 memset(G,0,sizeof(G));
31 memset(indegree,0,sizeof(indegree));
32 for(i=1;i<=m;i++)
33 {
34 scanf("%d%d",&a,&b);
35 if(G[a][b] == 0)
36 {
37 G[a][b]=1;
38 indegree[b]++;
39 }
40 }
41 toposort();
42 for(i=0;i<n;i++)
43 {
44 if(i != n-1)
45 printf("%d ",q[i]);
46 else
47 printf("%d",q[i]);
48 }
49 printf("\n");
50 }
51 return 0;
52 }
