#pragma GCC optimize("Ofast,unroll-loops")
#include<bits/stdc++.h>
#define int long long
//#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP     ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe  int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define pb push_back
#define checktime   cerr << (double)clock() / CLOCKS_PER_SEC * 1000  << " ms";
using namespace std;
#define getchar_unlocked getchar

inline int scan()
{
    char c = getchar_unlocked();
    int x = 0;
    while(c<'0'||c>'9')
    {
        c=getchar_unlocked();
    }
    while(c>='0'&&c<='9')
    {
        x=(x<<1)+(x<<3)+c-'0';
        c=getchar_unlocked();
    }
    return x;
}

void phongbeo();
const int inf=1e9;
const int mod2=1e9+9;
const int  mod1=998244353;
struct icd
{
    long double a;
    int b;
};
struct ib
{
    int a;
    int b;
};
struct ic
{
    int a,b,c;
};
struct id
{
    int a,b,c,d;
};
struct ie
{
    int a,b,c,d,e;

};

int n,m,s1,s2,s4,s3,sf,k,s5,s6,mx,s7,s8,s9,mx2,res,dem2=0,dem=0,s33,dem3,dem4,l,r,mid,l2,r2,center;
int  i,s10,s12;
int kk;
int el=19;
main()
{
#ifndef ONLINE_JUDGE
    ///  fin(task);
///    fou(task);
#endif
    NHP
    /// cin>>s1;
   // modwwe
    phongbeo(),down
    // checktime
}
vector<int> v[200001];
bool c[200001];
int f[200001];
vector<int>topo;
 void dfs(int x)
  {
       for(auto f:v[x]){
         if(c[x]==0)
        dfs(f);
        }
         topo.pb(x);
  }
void phongbeo()
{
 cin>>n>>m;
 for(int i=1;i<=m;i++)
     cin>>l>>r,v[l].pb(r),c[r]++;
 for(int i=1;i<=n;i++)
     if(!c[i]) dem++;
     assert(dem==0);
 }