#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define F first
#define S second
#define pb push_back
typedef long long ll;
typedef pair<ll, ll> pii;
typedef vector<ll> vi;

int main() {
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(cin.failbit);
	ll tests;cin>>tests;
	while(tests--){
		ll n,m;cin>>n>>m;
		vi a(m);rep(i,0,m)cin>>a[i];
		vi og=a;

		vi o=a;sort(all(o));
		vi ps(m+1,0);
		rep(i,0,m)ps[i+1]=o[i]+ps[i];
		ll hi = min(n,m);
		rep(k,0,min(n,m)){
			ll right = k*(n-k);
			ll i = lower_bound(all(o),k+1)-o.begin();
			ll left = ps[m]-ps[i]-(m-i)*k;
			// cout<<k<<' '<<right<<" "<<left<<' '<<(ps.back()-ps[i])<<' '<<((m-i)*k)<<endl;
			if(left<=right) hi=min(hi,(ll)k);
		}
		ll k = hi;
		cout<<k<<'\n';
		vector<vector<bool>> g(n,vector<bool>(m,false));
		rep(i,0,n)a[i]=max(a[i],k);
		vi b=a;rep(i,0,m)b[i]-=k;
		rep(i,0,k){
			ll y = n-k+i;
			rep(x,0,m){
				g[y][x]=true;
				while(b[x]>0 && y>0 && !g[y-1][x]){
					g[--y][x]=true;
					b[x]--;
				}
			}
		}
		rep(x,0,m){
			ll tot = 0;
			rep(y,0,n){
				tot += g[y][x];
				if(tot>og[x]) g[y][x]=false;
			}
		}
		rep(i,0,n){
			rep(j,0,m)cout<<(g[i][j]?'#':'.');
			cout<<'\n';
		}


	}
}