/**************************************************************

     Problem: 4010

     User: Tunix

     Language: C++

     Result: Accepted

     Time:820 ms

     Memory:4520 kb

 ****************************************************************/

 //Huce #7 C

 #include<queue>

 #include<vector>

 #include<cstdio>

 #include<cstdlib>

 #include<cstring>

 #include<iostream>

 #include<algorithm>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 using namespace std;

 int getint(){

     int v=,sign=; char ch=getchar();

     while(ch<''||ch>'') {if (ch=='-') sign=-; ch=getchar();}

     while(ch>=''&&ch<='') {v=v*+ch-''; ch=getchar();}

     return v*sign;

 }

 typedef long long LL;

 const int N=,INF=~0u>>;

 /*******************template********************/

 int to[N<<],next[N<<],head[N],cnt;

 void add(int x,int y){

     to[++cnt]=y; next[cnt]=head[x]; head[x]=cnt;

 }

 int n,m,du[N];

 void init(){

     n=getint(); m=getint();

     cnt=; memset(head,,sizeof head);

     memset(du,,sizeof du);

     int x,y;

     F(i,,m){

         x=getint(); y=getint();

         swap(x,y);

         add(x,y); du[y]++;

     }

 }

 int ans[N],tot;

 void solve(){

     priority_queue<int>Q;

     F(i,,n) if (!du[i]) Q.push(i);

     tot=;

     while(!Q.empty()){

         int x=Q.top(); Q.pop();

         ans[++tot]=x;

         for(int i=head[x];i;i=next[i]){

             du[to[i]]--;

             if (du[to[i]]==) Q.push(to[i]);

         }

     }

     if (tot==n) {D(i,tot,) printf("%d ",ans[i]); puts("");}

     else puts("Impossible!");

 }

 int main(){

 #ifndef ONLINE_JUDGE

     freopen("C.in","r",stdin);

 //  freopen("output.txt","w",stdout);

 #endif

     int T=getint();

     while(T--){

         init();

         solve();

     }

     return ;

 }