#include<bits/stdc++.h>
using namespace std;
int D,m,n;
struct Node{
    priority_queue<int,vector<int>,greater<int> > q;
};
Node data[100001];
bool done[100001],flag,in[100001];        
deque<int> p;
void dfs(int now)
{
    if(done[now]==true) return;    
    while(!data[now].q.empty())
    {
        int x=data[now].q.top();
        data[now].q.pop();
        dfs(x);
    }        
    done[now]=true;
    if(in[now]==true) flag=true;
    p.push_back(now);
    in[now]=true;
    return;
}
int main()
{
    freopen("dishes.in","r",stdin);
    freopen("dishes.out","w",stdout);
    cin>>D;
    while(D>0)
    {
        D--;
        memset(done,0,sizeof done);
        memset(in,0,sizeof in);
        p.clear();
        flag=false;
        cin>>n>>m;
        for(int i=1;i<=m;++i)
        {
            int a,b;
            cin>>a>>b;
            data[b].q.push(a);
        }
        for(int i=1;i<=n;++i)
            dfs(i);
        if(flag==true) 
        {
            cout<<"Impossible!"<<endl;
            continue;
        }
        while(!p.empty())
        {
            cout<<p.front()<<' ';
            p.pop_front();
        }
        cout<<endl;
    }
    return 0;
}