#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1000010;
int h[N], e[N], ne[N], idx;
void add(int a, int b)
{
    e[idx] = b;
    ne[idx] = h[a];
    h[a] = idx++;
}
int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        memset(h, -1, sizeof h);
        int n, m;
        cin >> n >> m;
        for (int i = 1; i <= m; i++)
        {
            int a, b;
            cin >> a >> b;
            add(a, b);
        }
        for (int i = 1; i <= n; i++)
        {
            for (int j = h[i]; j != -1; j = ne[j])
            {
                cout << e[j] << ' ';
            }
            cout << endl;
        }
    }
    return 0;
}