//TopSort拓扑排序 邻接表 优先队列实现字典序 #include<iostream> #include<algorithm> #include<cstdio> #include<cstring> #include<cmath> #include<cstdlib> #include<queue> using namespace std; #define inf 0x3f3f3f3f #define why 100005 struct node { int next,to; }a[500005]; int h[why],cnt,n,In[why],ans[why],m; priority_queue<int,vector<int>,greater<int> >q; inline void Add(int x,int y) { cnt++; a[cnt].to=y; a[cnt].next=h[x]; h[x]=cnt; } inline int redn() { int ret=0,f=1; char ch=getchar(); while(!isdigit(ch)) { if(ch=='-')f=-f; ch=getchar(); } while(isdigit(ch)) { ret=ret*10+ch-'0'; ch=getchar(); } return f>0?ret:-ret; } inline bool TopSort() { register int i,u; int t=0,now,y; for(i=1;i<=n;++i)if(!In[i])q.push(i); while(!q.empty()) { now=q.top(); q.pop(); ans[++ans[0]]=now; ++t; for(u=h[now];u;u=a[u].next) { y=a[u].to; --In[y]; if(!In[y])q.push(y); } } return (t==n); } int main() { register int i; int _1,_2; n=redn(); m=redn()+1; while(--m) { _1=redn(); _2=redn(); Add(_1,_2); ++In[_2]; } if(TopSort())for(i=1;i<=ans[0];++i)printf("%d ",ans[i]); else printf("NO SOLUTION"); return 0; } 