#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
const int N = 1e6 + 10;
int h[N], e[N], ne[N], idx;
int t, n, m;

void add(int a, int b)
{
	e[idx] = b, ne[idx] = h[a], h[a] = idx++;
}

int main()
{
	cin >> t;

	while (t--)
	{
		memset(h, -1, sizeof h);
		
		idx = 0;
		
		int n, m;
		scanf("%d%d", &n, &m);
		while (m--)
		{
			int a, b;
			scanf("%d%d", &a, &b);
			add(a, b);
		}

		  for (int i = 1; i <= n; i++)
		  {
			for (int j = h[i]; j != -1; j = ne[j])
			{
				printf("%d ", e[j]);
			}
			puts("");
		  }

	}

	return 0;
}