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

using vi = vector<int>;
using ll = long long;
using pii = pair<int, int>;
using vvi = vector<vi>;

#define rep(i, a, b) for(int i = a; i < (b); i++)
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)

void solve() {
    int n, m;
    cin >> n >> m;

    vi inp(m);
    for (int i = 0; i < m; i++) cin >> inp[i];

    int last = -1;
    for (int i = 0; i < n; i++) if (inp[i] == n) last = i;

    vector<string> res(n);
    vi dp(n+1);
    for (int i = 0; i < m; i++) {
        int x = inp[i];

        vi inds(n);
        iota(all(inds), 0);
        if (i < last) {
            res[n-1].push_back('#');
            x--;
            inds.pop_back();
        }
        sort(all(inds), [&] (int u, int v) {
            return make_tuple(dp[u]-dp[u+1], dp[u], -u) < make_tuple(dp[v]-dp[v+1], dp[v], -v);
        });
        for (int j = 0; j < x; j++) res[inds[j]].push_back('#');
        for (int j = x; j < sz(inds); j++) res[inds[j]].push_back('.');
        for (int i = n; i > 0; i--) {
            dp[i] = max(dp[i], dp[i-1]+(res[i-1].back() == '#'));
        }
        for (int i = 0; i < n; i++) {
            dp[i+1] = max(dp[i+1], dp[i]);
        }
    }
    cout << dp[n] << "\n";
    for (string s : res) cout << s << "\n";
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    int t;
    cin >> t;
    while (t--) solve();

    return 0;
}