1 #include <bits/stdc++.h>
2
3 const int maxn = 102;
4 using namespace std;
5
6 int G[maxn][maxn];
7 int n,m;
8 int vis[maxn];
9 int topo[maxn],tmpN;
10 bool dfs(int u)
11 {
12 vis[u] = -1;//under visting
13 for(int v = 1; v <= n; v ++)
14 {
15 if(G[u][v])
16 {
17 if(vis[v]<0) return false;//loop
18 else if(!vis[v] && !dfs(v)) return false;
19 }
20 }
21 vis[u] = 1;
22 topo[--tmpN]=u;
23
24 return true;
25 }
26
27 bool toposort()
28 {
29 tmpN = n;
30 for(int u = 1; u <= n; u ++)
31 {
32 if(!vis[u])
33 if(!dfs(u))
34 return false;
35 }
36 return true;
37 }
38
39 void solve()
40 {
41 if(toposort())
42 {
43 for(int i = 0; i < n; i ++)
44 cout << topo[i] << " ";
45 cout << endl;
46 }
47 }
48
49 int main()
50 {
51 while(cin >> n >> m)
52 {
53 memset(G,0,sizeof(G));
54 memset(vis,0,sizeof(vis));
55 while(m --)
56 {
57 int tmp1,tmp2;
58 cin >> tmp1 >> tmp2;
59 G[tmp1][tmp2] = 1;
60 }
61 solve();
62 }
63 return 0;
64 }
