1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 using namespace std;
 5 int map[550][550], indegree[550], result[550];
 6 int n, m;
 7 void Tsort(){
 8     int m, k = 0;
 9     for(int i = 0; i < n; i++){
10         //*m = -1; 
11         for(int j = 1; j <= n; j++){
12             if(!indegree[j]){
13                 m = j; break;
14             }
15         }    
16            result[k++] = m; indegree[m]--;  //删点； 
19         for(int j = 1; j <= n; j++)      //删边； 
20             if(map[m][j])
21                 --indegree[j]; 
22     } 
23     for(int i = 0; i < k; i++){
24         if(i != 0)
25             printf(" %d", result[i]);
26         else
27             printf("%d", result[i]);
28     }
29     printf("\n");
30 }
31 int main()
32 {
33     while(~scanf("%d %d", &n, &m))
34     {
35         memset(map, 0, sizeof(map));
36         memset(indegree, 0, sizeof(indegree));
37         for(int i = 0; i < m; i++)
38         {
39             int a, b;
40             scanf("%d %d", &a, &b);
41             if(!map[a][b]){   //去重； 
42                 map[a][b] = 1; 
43                 indegree[b]++;
44             }
45         }
46         Tsort();
47     }
48     return 0;
49 }