// MagicDark
#include <bits/stdc++.h>
#define debug cerr << "[" << __LINE__ << "] "
#define SZ(x) (int) x.size() - 1
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> inline void chkmax(T &x, T y) {x = max(x, y);}
template <typename T> inline void chkmin(T &x, T y) {x = min(x, y);}
template <typename T> inline void read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	x *= f;
}
const int N = 2e5 + 10;
int n, m, a[N], f[N], t[N];
bool check(int x) {
	F(i, 1, n) f[i] = 0;
	int r = n;
	F(i, 1, m) {
		t[i] = r;
		int l = r - a[i] + 1;
		if (l < 1) return false;
		DF(j, r, l) chkmax(f[j], f[j - 1] + 1);
		while (f[r - 1] == x) r--;
	}
	return true;
}
void zhk() {
	read(n), read(m);
	bool flag = true;
	F(i, 1, m) {
		read(a[i]);
		flag &= !a[i];
	}
	if (flag) {
		cout << "0\n";
		F(i, 1, n) {
			F(j, 1, m)
				cout << '.';
			cout << '\n';
		}
		return;
	}
	// sort(a + 1, a + n + 1);
	int l = 0, r = n;
	while (l + 1 < r) {
		int mid = (l + r) >> 1;
		if (check(mid)) r = mid;
		else l = mid;
	}
	check(r);
	// F(i, 1, m) debug << i << " " << t[i] << " " << a[i] << endl;
	cout << r << '\n';
	F(i, 1, n) {
		F(j, 1, m) {
			if (i >= t[j] - a[j] + 1 && i <= t[j]) cout << '#';
			else cout << '.';
		}
		cout << '\n';
	}
}
signed main() {
	int _ = 1;
	cin >> _;
	while (_--) zhk();
	return 0;
}
/* why?
*/