#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define PII pair<int,int>
#define x first
#define y second
void solve() {
	int n,k;
	cin>>n>>k;
	vector<vector<int>> a(n+1,vector<int>(n+1));
	vector<vector<int>> v(n+1,vector<int>(n+1));
	if((n%2==0)&&((n/2)%2==0)&&(k==n-1)){
		vector<int> b(n+1);
		for(int i=1;i<=n/2;i++){
			for(int j=1;j<=n;j++){
				b[j]=0;
			}
			for(int j=1;j<=n/2;j+=2){
				for(int k=j;k<=n;k++){
					if(a[i][j]==0&&v[j][k]==0&&b[k]==0){
						v[j][k]=1;
						b[k]=1;
						a[i][j]=k;
						a[i][k]=j;
					    if(k&1) a[i][j+1]=k+1,a[i][k+1]=j+1,b[k+1]=1;
					    else a[i][j+1]=k-1,a[i][k-1]=j+1,b[k-1]=1;
						break;
					}
				}
			}
		}
		for(int i=n/2+1;i<=n;i++){
			for(int j=1;j<=n/2;j++){
				a[i][j]=n+1-a[n-i+1][j];
			}
		}
		for(int i=1;i<=n/2;i++){
			for(int j=n/2+1;j<=n;j++){
				a[i][j]=n+1-a[i][n-j+1];
			}
		}
		for(int i=n/2+1;i<=n;i++){
			for(int j=n/2+1;j<=n;j++){
				a[i][j]=n+1-a[i][n-j+1];
			}
		}
		set<int> st[n+1];
		for(int i=2;i<=n;i++){
			for(int j=1;j<=n;j++){
				st[j].insert(a[i][j]);
			}
		}
		for(int i=1;i<=n;i++){
			if(st[i].size()!=n-1){
				cout<<"Impossible\n";
				return;
			}
		}
		for(int i=2;i<=n;i++){
			for(int j=1;j<=n;j++){
				st[j].insert(a[i][j]);
				if(j!=1) cout<<" "<<a[i][j];
				else cout<<a[i][j];
			}cout<<"\n";
		}
	}else{
		cout<<"Impossible\n";
	}
}
signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--) {
		solve();
	}
	return 0;
}