#include<bits/stdc++.h>
#define rep(x,y,z) for(int x=y;x<=z;x++)
#define drep(x,y,z) for(int x=y;x>=z;x--)
#define ull unsigned long long
#define ll long long
using namespace std;
inline int read()
{
	int x=0;bool flag=1;char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-')flag=0;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
	if(flag) return x;
	return ~(x-1);
} 
inline void write(int x)
{
	if(x<0) {x=~(x-1);putchar('-');}
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
//
const int N=1e5+50;
int tc,nc,mc;
int YN;
int ans[N],ansj;
struct SR
{
	int s1;
	int s2;
}s[N];
bool cmp(SR x,SR y)
{
	if(x.s1!=y.s1) return x.s1<y.s1;
	return x.s2<y.s2;
}
int ha[N],hb[N];
struct qxx
{
	int ar;
	int nx;
}a[N<<1],b[N<<1];//a:往下，b:往上 
int aj;
inline void ADD(int x,int y)
{
	a[++aj].ar=x;
	a[aj].nx=ha[y];
	ha[y]=aj;
	b[aj].ar=y;
	b[aj].nx=hb[x];
	hb[x]=aj;
}
int sz[N];//前置条件的多少 
priority_queue<int,vector<int>,greater<int> > q;//小根堆 
int j[N];
void BL(int cl)
{
	j[cl]=1;
	for(int i=ha[cl];i;i=a[i].nx)
	{
		sz[cl]++;
		if(j[a[i].ar]) YN=1;
		if(!sz[a[i].ar]&&ha[a[i].ar]) BL(a[i].ar);
	}
	j[cl]=0;
}
void BCL(int cl)
{
	j[cl]=1;
	if(!sz[cl]) 
	{
		q.push(cl);
		return;
	}
	for(int i=ha[cl];i;i=a[i].nx)
	{
		if(j[a[i].ar]) continue;
		BCL(a[i].ar);
	}
}
void bfs()
{
	int z;
	while(q.size())
	{
		z=q.top();
		q.pop();
		ans[++ansj]=z;
		for(int i=hb[z];i;i=b[i].nx)
		{
			sz[b[i].ar]--;
			if(j[b[i].ar]&&sz[b[i].ar]==0) q.push(b[i].ar);
		}
	}
}
void solve()
{
	memset(ha,0,sizeof(ha));
	memset(hb,0,sizeof(hb));
	memset(sz,0,sizeof(sz));
	memset(j,0,sizeof(j));
	aj=ansj=YN=0;
	nc=read(),mc=read();
	rep(i,1,mc) s[i].s1=read(),s[i].s2=read();
	sort(s+1,s+1+mc,cmp);
	rep(i,2,mc) if(s[i-1].s1==s[i].s1&&s[i-1].s2==s[i].s2) s[i-1].s1=s[i-1].s2=0;
	rep(i,1,mc) if(s[i].s1&&s[i].s2) ADD(s[i].s1,s[i].s2);
	rep(i,1,nc) if(!sz[i]&&ha[i]) BL(i);
	if(YN==1)
	{
		cout<<"Impossible!\n";
		return;
	} 
	rep(i,1,nc) if(!j[i]) BCL(i),bfs();
	rep(i,1,nc) write(ans[i]),putchar(32);
	putchar(10);
}
int main()
{
    freopen("dishes.in","r",stdin);
	freopen("dishes.out","w",stdout);
    tc=read();
    rep(i,1,tc) solve();
    return 0;
}