#include<bits/stdc++.h>
using namespace std;
const int N = 110;

void slove()
{
	int ans;
	int indegree[N]={0};
	int outdegree[N]={0};
	queue <int> q;
	vector<int>a[N];
	int n,m;
	cin >> n>>m;
	for (int i = 1; i <= m; i++)		//存图
	{
		int x,y;
		cin>>x>>y;
		a[x].push_back(y);
	//	a[y].push_back(x);
		indegree[y]++;
		outdegree[x]++;
	}
/*		for(int i = 1 ; i <=n ; i++ )
	{
		cout<<indegree[i]<<" ";
	}
	cout<<endl;
	for(int i = 1 ; i <=n ; i++ )
	{
		cout<<outdegree[i]<<" ";
	}
	cout<<endl;
	cout<<endl;*/
	for(int i = 1 ; i <=n ; i++ )
	{
		if(indegree[i]==outdegree[i]) 
		{
			ans = i ;
			break;
		}
	}
	
	for (int i = 1; i <= n; i++)
	{
		if (indegree[i] == 0) q.push(i);
	}
	while(!q.empty())
	{
		int x = q.front(); q.pop();
		for (int i = 0; i < a[x].size(); i++)
		{
			int t = a[x][i];
			indegree[t]--;
			if (indegree[t]==0)
				q.push(t);
		}
	}
	for(int i = 1 ; i <=n ; i++ )
	{
		if(indegree[i]!=0) 
		{
			for(int i = 1 ; i <= n ; i++)
				cout<<'0';
			return;
		}
	}
	for(int i = 1; i <= n ; i++ )
	{
		if(i==ans) cout<<'1';
		else cout<<'0';
	}
}
int main()
{
	int tcase;
	cin>>tcase;
	while(tcase--)
	{
	slove();
	cout<<endl;
	}
	
	return 0;
}