#include<bits/stdc++.h>
using namespace std;
int const N=1e3+10;
int f[N][N],a[N][N];
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
void solve(){
    int n,m;cin>>n>>m;
    if (m==1) return cout<<"Impossible\n",void();
    if (n<=3){
        for (int i=0;i<(1<<(n*n));++i){
            for (int j=0;j<n;++j)
                for (int k=0;k<n;++k)
                    if (i>>(j*n+k)&1) a[j][k]=1;
                    else a[j][k]=0;
            int res=0;
            for (int j=0;j<n-1;++j)
                for (int k=0;k<n;++k)
                    if (a[j][k]!=a[j+1][k]) ++res;
            for (int j=0;j<n-1;++j)
                for (int k=0;k<n;++k)
                    if (a[k][j]!=a[k][j+1]) ++res;
            if (res==m){
                cout<<"Possible\n";
                for (int i=0;i<n;++i,cout<<'\n')
                    for (int j=0;j<n;++j) cout<<a[i][j];
                return;
            }
        }
        cout<<"Impossible\n";
        return;
    }
    vector<int>p(10),t(10);
    for (int i=1;i<=n;++i)
        for (int j=1;j<=n;++j)
            a[i][j]=f[i][j]=0;
    int res=0;
    for (int i=1;i<=n;++i)
        for (int j=1;j<=n;++j)
            if (!((i+j)&1)){
                for (int k=0;k<4;++k){
                    int x=i+dx[k];
                    int y=j+dy[k];
                    if (x<1 || x>n || y<1 || y>n) continue;
                    ++f[i][j];
                }
                ++t[f[i][j]];
            }
    int fl=0;
    for (int i=0;2*i<=m && i<=t[2]+2*t[4];++i){
        if ((m-2*i)%3) continue;
        if (t[3]<((m-2*i)/3)) continue;
        p[3]=(m-2*i)/3;
        if (i<=t[2]) p[2]=i,p[4]=0;
        else{
            p[4]=0;if (i&1) --i,p[2]=1;
            if (i/2<=t[4]) p[4]=i/2;
            else p[4]=t[4],p[2]+=i-t[4]*2;
        }
        fl=1;break;
    }
    if (!fl) return cout<<"Impossible\n",void();
    cout<<"Possible\n";
    for (int i=1;i<=n;++i,cout<<'\n')
        for (int j=1;j<=n;++j){
            if (!p[f[i][j]]){cout<<"0";continue;}
            --p[f[i][j]],cout<<"1";
        }
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    int t;cin>>t;
    while (t--) solve();
    return 0;
}