#include <bits/stdc++.h>
#define int long long
const int N=1e5+5;
using namespace std;
int n,m;
namespace sub1
{
	int get(int x,int y){return 4-(x==1||x==n)-(y==1||y==n);}
	void out(int i2,int i3,int i4)
	{
		cout<<"Possible\n";
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				if((i&1)==(j&1))
				{
					if(i2&&get(i,j)==2){i2--;goto ff;}
					if(i3&&get(i,j)==3){i3--;goto ff;}
					if(i4&&get(i,j)==4){i4--;goto ff;}
					cout<<1;
					continue;
				}
				ff:;
				cout<<0;
			}
			cout<<'\n';
		}
	}
	void solve()
	{
		if(m==2*n*(n-1)-1){cout<<"Impossible\n";return;}
		int i3max=(n-3)*2,maxn=2*n*(n-1);
		for(int i2=0;i2<=4;i2++)
		for(int i3=0;i3<=i3max;i3++)
		{
			if(maxn-m-i2*2-i3*3<0)break;
			if((maxn-m-i2*2-i3*3)%4==0&&(maxn-m-i2*2-i3*3)/4<=((n-2)*(n-2)+1)/2)
			{out(i2,i3,(maxn-m-i2*2-i3*3)/4);return;}
		}
	}
}
namespace sub2
{
	int get(int x,int y){return 4-(x==1||x==n)-(y==1||y==n);}
	void out(int i2,int i3,int i4)
	{
		cout<<"Possible\n";
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				if((i&1)==(j&1))
				{
					if(i2&&get(i,j)==2){i2--;goto ff;}
					if(i3&&get(i,j)==3){i3--;goto ff;}
					if(i4&&get(i,j)==4){i4--;goto ff;}
					cout<<1;
					continue;
				}
				ff:;
				cout<<0;
			}
			cout<<'\n';
		}
	}
	void solve()
	{
		if(m==2*n*(n-1)-1){cout<<"Impossible\n";return;}
		int i3max=(n-2)*2,maxn=2*n*(n-1);
		for(int i2=0;i2<=2;i2++)
		for(int i3=0;i3<=i3max;i3++)
		{
			if(maxn-m-i2*2-i3*3<0)break;
			if((maxn-m-i2*2-i3*3)%4==0&&(maxn-m-i2*2-i3*3)/4<=(n-2)*(n-2)/2)
			{out(i2,i3,(maxn-m-i2*2-i3*3)/4);return;}
		}
	}
}
int a[6][6];
int check()
{
	int sum=0;
	for(int i=1;i<n;i++)
	for(int j=1;j<=n;j++)
	if(a[i][j]!=a[i+1][j])
	sum++;
	for(int i=1;i<=n;i++)
	for(int j=1;j<n;j++)
	if(a[i][j]!=a[i][j+1])
	sum++;
	return sum;
}
void dfs()
{
	for(int S=0;S<1<<(n*n);S++)
	{
		for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
		a[i][j]=(S>>((i-1)*n+(j-1)))&1;
		if(check()==m)
		{
			cout<<"Possible\n";
			for(int i=1;i<=n;i++)
			{
				for(int j=1;j<=n;j++)
				cout<<a[i][j];
				cout<<'\n';
			}
			return;
		}
	}
	cout<<"Impossible\n";
}
void solve()
{
	cin>>n>>m;
	if(m==1){cout<<"Impossible\n";return;}
	if(m<=n)
	{
		cout<<"Possible\n";
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			if(i==1&&j<m)cout<<1;
			else cout<<0;
			cout<<'\n';
		}
		return;
	}
	if(n<=4){dfs();return;}
	if(n&1){sub1::solve();return;}
	else{sub2::solve();return;}
}
int T;
signed main()
{
//	freopen("genshin.in","r",stdin);
//	freopen("genshin.out","w",stdout);
	ios::sync_with_stdio(false);cin.tie(0);
	cin>>T;
	while(T--)solve();
}